Our staff is carefully selected to create a professional, positive, and nurturing experience for each girl. Many staff are in residence at the Choir School throughout the course and participate in all aspects of the course (except rehearsals) with the girls, including meals and outings. We strive to build a sense of community among one another, create a high-level musical experience and encourage an environment of kindness.

2022 Course Staff

Course Co-Directors

Rebecca Kellerman-Filsell
Margaret White

Music and Teaching Staff

Guest Music Director: Katherine Dienes-Williams
Vocal Coach and Music History Teacher: Jacqueline Horner-Kwiatek
Guest Organist and Music Theory Teacher: Janet Yieh
Course Organist: Jeremy Filsell

Student Support Staff

Course Chaplain: Mother Alison Turner
Nurse: Jennifer Euling Johnson
Housemother: Karen Wentling
Residential Life Coordinator: Emma Barnaby
Intern: Olivia Scarozza

Staff Biographies


Rebecca Kellerman-Filsell, Co-Director

Rebecca Kellerman-Filsell

Rebecca Kellerman-Filsell joins the Saint Thomas Girl Chorister Course after spending the previous 20+ years singing and teaching music in the Washington, DC metro area. She is the Music Associate for Children and Youth at Saint Thomas Church where she directs their new parish children’s choir, the Noble Singers, which includes boy and girl choristers ages 6-12. This new choir sings and leads worship at the 9am Mass.

Whilst in Washington, DC, Rebecca frequently appeared as soloist and chorister with The Washington Bach Consort, Opera Lafayette, The Washington National Cathedral and various other choral groups in the DC metro area and beyond. An avid choral singer, Rebecca served as section leader and Music Associate at Saint Alban’s Church, Washington, DC, where she reignited their children’s music ministry with a RSCM chorister program. She also served as vocal coach for the chorister program at Saint Paul’s K St. from 2014-2019. Her private studio includes students of all ages and abilities, but she specializes in teaching young singers. Rebecca holds both a Bachelor’s and a Master’s degree in Music from Shenandoah University, where she studied voice performance/pedagogy and music education. Rebecca lives in the heart of Manhattan with her husband, two sons and a spotted gecko. www.rebeccakellerman.com.


Margaret White, Co-Director

Margaret White

During the school year Margaret is a full-time member of Saint Thomas Choir School’s residential faculty, teaching Latin to grades 6-8 and English to grade 5. A lifelong New Yorker, Margaret attended the all-girls’ Brearley School for thirteen years and then Princeton University, where she earned her A.B. in English with minors in Theater and American Studies.

She began her career as a substitute teacher in all grades and several subjects at independent schools across Manhattan. After three years teaching middle school Latin and English at Marymount School of New York, she temporarily relocated to Massachusetts to earn her Ed.M. in Learning and Teaching at Harvard University. As a Choir School faculty member, a product of all-girls’ education, and a trained vocal musician herself, she eagerly looks forward to helping oversee the next stage of the Girl Chorister Course.

Outside of the classroom, Margaret enjoys reading and writing stories for young people (she also holds an MFA in Writing for Children and Young Adults) and spending time with her dog, Blaze. Her other interests include musical theater, baking, board games, and learning new languages.


Katherine Dienes-Williams, Music Director

Katherine Dienes-Williams

Katherine Dienes-Williams, MA, BMus, FRCO, LTCL, Hon. FRSCM, Hon. FGCM was appointed Organist and Master of the Choristers at Guildford Cathedral in January 2008 following six years as Director of Music at the Collegiate Church of St. Mary, Warwick. In May 2022 she was appointed the first ever female President of the Cathedral Organists’ Association.

Katherine was born and educated in Wellington, New Zealand and studied for a BA in Modern Languages and a BMus at Victoria University, Wellington. Katherine was Organ Scholar at Wellington Cathedral from 1988 to 1991 when she was appointed Assistant Organist there.

Katherine came to England in 1991 to take up the post of Organ Scholar at Winchester Cathedral and Assistant Organist at Winchester College. She has also held posts as Organist and Assistant Director of Music at the Metropolitan Cathedral of Christ the King, Liverpool, Assistant Organist and Director of the Cathedral Girls’ Choir at Norwich Cathedral prior to moving to Warwick as Director of Music at the Collegiate Church of St. Mary.

She is a Council member of the Royal College of Organists and a trustee of the Organists Charitable trust and is regularly asked to be a guest choral workshop leader for the Royal School of Church Music in the UK, South Africa, the USA, Canada and Australia. Katherine has given several organ recitals in the United Kingdom, New Zealand, Germany, U.S.A., Bermuda, the Netherlands, South Africa, Australia, Spain and Singapore. She has performed as organ soloist with the Royal Liverpool Philharmonic Orchestra, the Hallé, the City of London Sinfonia, Southern Pro Musica and the Royal Philharmonic Orchestra. In 2018 she performed the Saint-Saëns Organ Symphony in the London’s Royal Festival Hall with the Royal Philharmonic Orchestra, and again in May 2018 with Southern Pro Musica in Guildford Cathedral. She is also active as a composer, having received several commissions in the UK, the USA and New Zealand.

Katherine holds a Master of Arts in Music and Liturgy from Leeds University. She features both as organist and choral conductor on several recordings. She is in demand as a choral workshop leader in the UK, the USA and several other European countries. In summer 2019 she directed the St. Thomas’ girl choristers’ course in New York and in summer 2021 and 2022 she tutored on the Oundle Organists’ course in the UK. In 2022 she co-directed a Rodolfus Foundation junior choral course. Other interests include languages (her BA is in French and German), travel, reading and fitness. She is a Knight of the Grand Order of Vitéz and a Knight of the Order of St. Ladislau (Hungary). Katherine is married to Patrick Williams, and they have a daughter, Hannah, who is currently studying Music at Cambridge University.


Jacqueline Horner-Kwiatek, Vocal Coach and Music History Teacher

Rebecca Kellerman-Filsell

Dr. Jacqueline Horner-Kwiatek, mezzo-soprano, was a member of the world-renowned vocal quartet Anonymous 4 from 2000-2016. She recorded twelve award-winning CDs with the group, including American Angels which twice topped Billboard’s classical music charts, and The Cherry Tree, one of the top selling classical CDs of 2010. Anonymous 4′s performance of the Irish lament “Caoineadh” on Christopher Tin’s album Calling All Dawns, with Jacqueline as featured soloist, led to a Grammy for Best Classical Music Crossover Album. She is the Founder and Artistic Director of ModernMedieval, an organization created to promote performance and education in early and new music. It includes ModernMedieval Voices, a female vocal ensemble which fosters collaborative projects featuring early music in conjunction with music from later periods and newly commissioned works.

She has a reputation as a versatile and accomplished soloist, specializing in early and new music on both the concert and operatic stage. She has collaborated with many composers including Judith Weir, Karlheinz Stockhausen, Luciano Berio, Orlando Gough, Richard Einhorn, Andrew Toovey, Andrew Lovett, Louis Conti, Daniel Thomas Davis, Gregory Spears, Phil Kline and David Lang, singing with such distinguished new music ensembles such as Ensemble Modern Frankfurt, Ensemble Intercontemporain Paris, Singcircle, Continuum, Washington Square Contemporary Music Society, Ixion, Dogs of Desire, Ekmeles, S.E.M. Ensemble and the Locrian Chamber Ensemble.

She has appeared as a guest soloist with many early music ensembles both in Europe and the U.S., including The Washington Bach Consort DC, The Sixteen, The Bach Sinfonia, Carmel Bach Festival, St. Thomas Church NYC, Bach Vespers at Holy Trinity Lutheran NYC, Baltimore Consort, Bach Festival of Philadelphia, Armonia Nova, The Folger Consort, Parthenia, Sonnambula, Abendmusik, Hudson Chorale, and Fairfax Choral Society. Repertoire includes the mezzo/alto solos in Bach Magnificat, St Matthew and St John Passions, B Minor Mass and many cantatas, Vivaldi’s Gloria, Handel’s Messiah and Dixit Dominus, Durufle and Faure Requiem, Paine Mass in D and songs from the Elizabethan era for Parthenia’s acclaimed program When Music and Sweet Poetry Agree. She is a frequent soloist with Distinguished Concerts International New York, performing Calling All Dawns at Carnegie Hall and David Geffen Hall.

Jacqueline is also a voice teacher. She is a member of the Performance Faculty at Princeton University where she teaches voice, directs the Early Music Princeton Singers, and is Associate Director of the Certificate program in Consort Singing.. She gives residencies and vocal masterclasses at universities all over the US and offers seminars on vocal pedagogy to student composers, collaborating with them to develop and perform new pieces for the voice. She also lectures on vocal pedagogy and gives Ensemble Technique workshops with groups ranging from trios to choirs with 100+ members. She holds degrees from Queens University Belfast, Teacher’s College Columbia University and has a D.M.A. from The Juilliard School.


Janet Yieh, Guest Organist and Music Theory Teacher

Janet Yieh

Janet Yieh has been newly appointed Director of Music at Church of the Heavenly Rest on the Upper East Side in New York City. Most recently, she served as Associate Organist at Trinity Church, Wall Street in New York City where she played weekly services, directed the St. Paul’s Chapel Choir, accompanied the Grammy-nominated Trinity Choir and Trinity Youth Chorus, and worked closely with the music and liturgy departments.

An innovative concert recitalist and sacred music specialist, Janet was named one of ‘20 under 30’ promising artists by The Diapason magazine in 2017. She has performed concert tours throughout the United States and across the globe, with highlights including New York’s Alice Tully Hall, Washington’s National Cathedral, San Francisco’s Grace Cathedral, Yale University’s Woolsey Hall, Taipei’s Aletheia University Chapel, and Japan’s Momoyama St. Andrew’s University Chapel. She has collaborated with the Paul Winter Consort, the Washington Chorus at The Kennedy Center, and Trinity’s NOVUS NY orchestra at Carnegie Hall. She regularly premieres new works for the organ, and has been featured on the national radio show Pipedreams, New York’s WQXR, New Jersey’s WWFM, Connecticut’s WMNR, and two CD recordings, Julian Wachner: Symphony No. 1, Works for Orchestra and Voices (Musica Omnia/Naxos, 2014) and Celebrating the Skinner Organ (Schott, 2011).

A native of Alexandria, Virginia, Janet earned a Master’s of Musical Arts (2018) and Master’s Degree in Organ Performance (2017) from the Yale School of Music and Yale Institute of Sacred Music and a Bachelor of Music in Organ (2015) from the Juilliard School. While at Yale, she was appointed Organ Scholar at Christ Church, New Haven and Trinity Church on the Green, while also serving as Director of Music and Organist of the Berkeley Divinity School at Yale. Janet’s former teachers include Thomas Murray, Paul Jacobs, John Walker, Wayne Earnest and Victoria Shields.

In 2020, Janet served on the AGO National Steering Committee for the internationally broadcast AGO OrganFest 2020, and she co-founded a new platform ‘Amplify Female Composers’ with Carolyn Craig, which launched a December Advent Calendar Project of daily Advent and Christmas music by women composers sung by 25 international parish, cathedral and university choirs. She also joined a research team of 8 international musicians building a Women Composers Database for “A Great Host of Composers”. Janet taught on the faculty of the 2019 Cape Cod AGO Pipe Organ Encounter, and played as course organist for the 2019 RSCM Rhode Island Course and organ scholar for the 2018 RSCM Carolina Course at Duke University. She is a Colleague of the American Guild of Organists, an executive board member of the New York City AGO, and a member of the Association of Anglican Musicians. www.janetyieh.com.


Jeremy Filsell, Course Organist

Jeremy Filsell

Jeremy Filsell is the current Organist and Director of Music at Saint Thomas Church Fifth Avenue. As a U.S. Citizen and a British Citizen, he is uniquely placed to lead the Saint Thomas Choir of Men and Boys, which owes much of its existence to the great English choral tradition since T. Tertius Noble was invited to found the Saint Thomas Choir School in 1919.

Jeremy Filsell has been hailed as one of only a few virtuoso performers as both pianist and organist. He has appeared as a solo pianist in Russia, Scandinavia, New Zealand and throughout the USA and UK. His concerto repertoire encompasses Bach, Mozart and Beethoven through to Shostakovich, John Ireland and Rachmaninov. He has recorded the solo piano music of Herbert Howells, Bernard Stevens, Eugene Goossens and Johann Eschmann and recently released were discs of Litaize’s organ music, Rachmaninov’s first and second piano concertos and two of French Mélodies accompanying Michael Bundy (baritone). Jeremy is on the international roster of Steinway Piano Artists and has recorded for BBC Radio 3, USA, and Scandinavian radio networks in solo and concerto roles.

His discography comprises more than 35 solo recordings. Gramophone magazine commented on the series of 12 CDs comprising the première recordings of Marcel Dupré’s complete organ works for Guild that it was ‘one of the greatest achievements in organ recording’. In 2005, Signum released a 3-disc set of the six organ symphonies of Louis Vierne, recorded on the 1890 Cavaillé-Coll organ in St. Ouen, Rouen, BBC Radio 3’s Discs of the Week.

He has taught at universities, summer schools, and conventions in both the UK and USA and has served on international competition juries in England and Switzerland. Recent solo engagements have taken him across the USA and UK and to Germany, France, Finland, Sweden, Norway, Australia and New Zealand. In North America, he concertizes under the auspices of Philip Truckenbrod Concert Artists.

Brought up as a chorister in Coventry, England, Jeremy Filsell was charged with the direction of a men & boys choir there while still a High School student. Studying with Nicolas Kynaston and Daniel Roth, he read for a first degree as Organ Scholar of Keble College, Oxford University before completing graduate studies in piano at the Royal College of Music in London. He was awarded a Ph.D. in Musicology at Birmingham Conservatoire/BCU for research on aesthetic and interpretative issues in the music of Marcel Dupré.

A former Assistant Organist of Ely Cathedral and Director of Music at St. Luke’s Chelsea in London, before moving to the USA in 2008, Jeremy held Academic and Performance lectureships at the Royal Academy of Music in London and the Royal Northern College of Music in Manchester, and was a lay clerk in the Queen’s choir at St. George’s Chapel, Windsor Castle. You can read more about Jeremy at his website: www.jeremyfilsell.com.


Mother Alison Turner, Course Chaplain

Mother Alison Turner

Mother Turner currently serves as Associate for Children & Family Ministry at Saint Thomas Church and School Chaplain at Saint Thomas Choir School. She was born in southeast England and has always been committed to parish life, especially in the areas of education and catechesis, liturgy, and music. She has a bi-vocational ministry, as both a teacher and priest.

Her education was rooted in Roman Catholic and Anglican multicultural schools in East London. She studied for her first degree and teaching qualifications at St Mary’s University College, Strawberry Hill, Twickenham (University of Surrey). She then received her MA in the area of Theology and Adult Education. Subsequently, she became a Head of School in two schools in Devon, the first in a rural setting and the most recent being Exeter Junior School, a large independent city school. In 2015, she joined her husband, Fr. Turner, in New York.

Mother Turner’s ministerial formation was based in Cambridge, and she was ordained priest in the Diocese of Chelmsford, at Michaelmas 1998. Her most recent ministerial position in the UK was as Priest Vicar in Exeter Cathedral, where she had particular interest and oversight of the nurture and catechesis of children and young people at local and Diocesan level.

Mother Turner recently graduated with a Masters in Sacred Theology from the General Theological Seminary in New York City. Her focus of study was Children’s ministry in the Episcopal Church. She has also completed further studies in Spiritual Direction.


Jennifer Euling Johnson, Nurse

Nurse Jennifer Euling Johnson is thrilled to be returning! As the mother of a St Thomas boy chorister (2004-2009) and now RN for the Girls Chorister Course, she ensures that each and every chorister has their medical needs anticipated and met. She is present 24/7 – on outings, in the choir stalls during services – wherever the girls are, she is there, toting her orange backpack full of medical supplies.

Outside of the Girls Course, Mrs. Johnson spends her time as a nurse at St Mary’s Hospital, singing alto in her husband’s choir at St Michael’s Church, Litchfield, CT, and caring for their beloved pups Raechel and Petey.


Karen Wentling, Housemother

Karen spent her childhood years in Bergen County, NJ. After receiving her BS in Physical Therapy at Hunter College, she worked at Stamford Hospital before becoming a full-time mother to six children. Karen has moved up and down the east coast: she lived in Greenwich CT, followed by many happy years in Acton MA, before returning to NYC. Her youngest son was a chorister at the Choir School for five years.

Besides her role as Housemother at the Choir School, Karen maintains a small Physical Therapy practice. She is an avid tennis player, and enjoys attending a weekly Bible study.


Emma Barnaby, Residential Life Coordinator

Emma Barnaby came to the St. Thomas Girl Chorister Course as a chorister in middle school and never wanted to leave. She has since been a floor leader, intern, and, since 2015, a staff member, and it is the highlight of her summer each year.

Ms. Barnaby holds a B.A. from the University of Toronto, where she majored in music history and theory, and an M.A. in musicology from the University of Pennsylvania, where she wrote a thesis on the history of professional child musicians in English cathedrals, with a particular focus on the absence (and relatively recent inclusion) of women and girls. She currently works at the University of Maryland, Baltimore County as an academic advisor for life science students and is passionate about education and student success. In her spare time, she is an avid knitter and enjoys hiking with her dog, Hobbes.


Olivia Scarozza, Intern

Olivia Scarozza is thrilled to be returning to the Girls’ Course after attending it herself from age 12-17. She is currently a student at Swarthmore College in Pennsylvania, where she studies voice and sings in the Chorus (and is undecided on what her major will be!). Olivia grew up in Connecticut where she sang as a chorister at St. Paul’s on the Green in Norwalk. Desperate for more choir in her life, Olivia was lucky enough to study at Rugby School in the U.K. for high school and happily sang seven days a week there for five years. Outside of the choral world, Olivia loves food (both cooking and eating), searching for second-hand clothes and reading fantasy novels.