[2] Protheroe started his career with his academic pursuits developing interest in music theory and composition during this time, his notable collaboration with the renowned Greek musician Vangelis get him into prominence during the late 1980s.
In 2000, he directed a series of staged performances of Xenakis' Oresteia at the Royal Opera House's Linbury Studio Theatre in Covent Garden, garnering rave acclaim.
However, in almost a full circle, Spectrum was brought together again in January 2000 to give the first professional performances in the newly-constructed Linbury Studio Theatre at the Royal Opera House, Covent Garden.
The English Chamber Choir was formed by the conductor David Measham as a splinter group from the London Symphony Chorus and formally constituted in 1972.
When David Measham left for Australia, Protheroe was appointed conductor and musical director and together he and the Choir have enjoyed over four decades of music-making, in venues ranging from the Royal Albert Hall to village churches in France and Switzerland, singing music from over six centuries in numerous languages and recording not only classical albums and CDs but also taking part in many live and recorded commercial productions.
It was in 1972 and '73 that the newly-formed Choir was invited to sing in the stage performances of the rock opera Tommy with The Who, and the 1973 shows at the Rainbow Theatre in Finsbury Park, London, were Protheroe's introduction to the commercial business of 'popular' music – an area in which he became immediately at home and frequently involved, alongside his more 'classical' engagements.
A few years after the ECC was founded a chamber orchestra, the English Players, was formed to accompany it in the choral/orchestral repertoire from the 17th century onwards, playing on period instruments as appropriate, both in the UK and Europe.
The Choir's unaccompanied (a cappella) repertoire ranges from mediaeval times to today – highlights including Thomas Tallis's 40-part motet Spem in alium which it has performed by invitation of the Lord Mayor of London at the Mansion House, and many compositions inspired by the music of the Eastern Church (and in particular Byzantine chant) including Sir John Tavener, Ivan Moody and the Greek-Canadian composer Christos Hatzis.
Together Protheroe and the ECC have a long list of recording credits which include The Byzantine Legacy (Sony Greece, 2000) EcleCtiCa (2008) and The Troparion of Kassiani (Naxos, 2011).
(See discography for more details) In recent years the ECC has enjoyed a successful association with the Belmont Ensemble and their conductor Peter G Dyson, taking part in many concerts at the Church of St Martin-in-the-Fields in Trafalgar Square, London.
After beginning as chorus master for The Who's Tommy, Protheroe has worked on films, television and radio commercials and in concerts with a wide variety of artists as conductor, musical director, arranger, composer and lyricist including John Anderson, Tangerine Dream, Black Sabbath, George Martin, Larry Adler, Barrington Pheloung, Dave Stewart, David Arnold, Roy Wood and Mark Almond.
In February 2023 he conducted the ECC in more prog rock concerts with Rick Wakeman and the English Rock Ensemble at The London Palladium Protheroe was lyricist, arranger, musical director, and vocal soloist on Eric Lévi's score to the French smash-hit comedy film Les Visiteurs (1993) and also on the album Era (1996) with over 6 million sales in mainland Europe and South America.
In recent years, Protheroe has been chorus master for many feature films, including Titus, Bless The Child, The Count of Monte Cristo, Reign of Fire, Gangs of New York, Johnny English, Sky Captain and the World of Tomorrow, The SpongeBob Squarepants Movie, and for the Spielberg/Hanks television series Band of Brothers.
In addition to Xenakis, Lina Lalandi had also introduced Protheroe and Ann to the work of the Greek Byzantine Choir, under its director Lycourgos Angelopoulos.
And around this time other composers, notably John Tavener in England and Christos Hatzis in Canada, were beginning to write music inspired by the Byzantine tradition.
Protheroe has not only conducted, performed and recorded music from all these traditions, but also instigated and directed a number of festivals and concert series in London (see Project Direction below) and participated in a European Union project 'Medimuses' which set out to document the performing traditions of the Magreb in partnership with several partner organisations, including Écume (Échanges Culturels en Mediterranée) in Marseilles, for whom he also conducted Purcell's opera Dido and Aeneas in Tunis (ancient Carthage) with cast and musicians all drawn from around the Mediterranean, the first opera to have been produced in Tunisia for 85 years.
He has collaborated with Cappella Romana, the US vocal ensemble based in Portland, Oregon and Seattle directed by Alexander Lingas, which also pioneers contemporary works related to the Byzantine tradition.
Protheroe has conducted in many countries in Europe, Russia, the US and South America in concerts, broadcasts and recordings with orchestras, choruses and ensembles including such diverse groups as Grand Choir: International classical engagements include conducting Purcell's Dido and Aeneas in Tunis (Carthage) in 2002 for a European Union-supported project with cast and musicians all drawn from around the Mediterranean, the first opera to have been produced in Tunisia for 85 years.
This track has been used internationally in many different media and is especially familiar to many millions throughout Europe and South America, and uses range from television commercials to computer games, and even wrestling and martial arts.
The Byzantine Festival also presented events in Plovdiv, Bulgaria in June 1999 as part of Greece's contribution to European Cultural Month there, and in April 2000 at the Megaron Concert Halls in Athens.
Another major Byzantine Festival was presented in London in March 2004, including another Royal Concert in St Paul's Cathedral in which Protheroe conducted the world première of Christos Hatzis's Troparion of Kassiani.
He was, for the Byzantine Festival, on the Steering Committee of MediMuses, a three-year international project run from Greece and funded by the European Commission researching and promoting the history and performance of the modal music (maqam) of the Eastern and South Mediterranean.
In this connection in February 2005 he hosted a unique international seminar on The Mediterranean Voice in London with many leading performers and recording artists from the Middle East and North Africa, and a major concert of ensembles from Beirut and Thessaloniki.
In 2008 he was Single Joint Expert in the Busted case, and also in 2008 was engaged by ITV Productions as Consultant Musicologist to the new karaoke game-show Who Dares, Sings!.
He is author of a major chapter on his experience as a forensic musicologist and expert witness in court for a forthcoming international publication: "Music Borrowing And Copyright Law" https://www.bloomsbury.com/uk/music-borrowing-and-copyright-law-9781509949403/, being published in October 2023.
Protheroe is a member of the Academy of Experts, BASCA (the British Academy of Composers, Songwriters and Authors), PRS (Performing Right Society), MCPS (Mechanical Copyright Protection Society), PPL (Phonographic Performance Limited), SACEM (Société des Auteurs, Compositeurs et Éditeurs de Musique, France), SDRM (Société pour l'Administration du Droit de Reproduction Mécanique des Auteurs, Compositeurs et Éditeurs, France) and the Musicians' Union.