Wilhelm Theunissen hails from South Africa. He completed his vocal studies under the guidance of Prof. Werner Nel at Potchefstroom University, received singing lessons in Italy and Germany and finally decided to devote his career to Oratorio and teaching. He was a lecturer of singing at the Musicon and head of the Youth Opera Studio at Sand du Plessis Theatre, Bloemfontein, where he developed programmes that opened the education system to less privileged students and helped launch several black professional singers.

He performed in all the major centres of that country. Notable highlights include the world premiere of the Martin Watt Requiem with the National Symphony Orchestra,

Bach's B Minor Mass with the 'Leipzig Vokale Ensemble and Bach's St John Passion for the State Theatre in Pretoria. He enjoyed a particular association with Dr. Barry Smith of St. George's Cathedral in Cape Town where he performed in several memorable concerts, including Bach's St Matthew Passion and 'St. Nicolas' by Benjamin Britten.

Since moving to the UK in 2003 he has already started making his mark on the concert platform having performed in such prestigious venues as Worcester Cathedral, Leeds Town Hall and Colston Hall in Bristol. This includes singing his favourite part of the Evangelist in Bach's St. Matthew and St. John Passions, doing the solo parts in Handel's Messiah and Ode to St. Caecila, Haydn's Creation and the Verdi Requiem. He has also received favourable reviews for his performances of the tenor parts in Britten's 'The Company of Heaven' at' Three Choirs Festival and Elgar's Coronation Ode with the Royal Liverpool Philharmonic last year.

He currently teaches singing at the Royal Grammar and Alice Ottley School and Elgar School of Music in Worcester and sings professionally for the BBC National Chorus of Wales.