Sidwell's contribution as organist and music director both at St Clement Danes (1957-92) and Hampstead Parish Church (1946-92) amounted to an astonishing combined total of over 80 years' service. Add to this his work in founding and conducting the London Bach Orchestra (1967-81), the Hampstead Choral Society (1946-81) and the Martindale Sidwell Singers (1956-92), recording and broadcasting commitments, teaching the organ at Trinity College of Music and the Royal Academy of Music (1963-84), not to mention fulfilling duties as a Professor at the Royal School of Church Music (1958-66), and it becomes clear why "Martin" became a legend.
He was born in Warwickshire in 1916 and christened John William Martindale, a combination of his father's Christian names and his mother's maiden name. John William senior was an enthusiastic amateur musician, and at the age of seven the young Martindale won a place as a chorister (and pupil in the choir school) at Wells Cathedral. By the time his voice broke he was already a talented organist, having studied at the cathedral with Conrad Eden. At just 16, in 1932, he was appointed cathedral sub-organist.
As with so many of his generation, the Second World War interrupted plans and ambitions. He served with the Royal Engineers, working on south coast defences but was also involved in many risky expeditions across the Channel. In 1944 he married the pianist and harpischordist Barbara Hill, a noted performer herself, later to become Professor of Piano at the Royal College of Music.
Somehow Sidwell managed to maintain a strong wartime connection to music- making in the Midlands, becoming respectively director of music at Warwick School, organist of Holy Trinity Church, Leamington Spa and conductor of the Leamington Spa Choral Society.
These proved the springboard for his achievements at Hampstead Parish Church after the war, when he came to London for organ studies under the highly regarded C.H. Trevor at the Royal Academy of Music. He was appointed to Hampstead in 1946, at a time when its strong musical tradition had been decimated as a by-product of the hostilities.
In a remarkably short period he established the choir of men and boys as one of the finest in the country, not excluding cathedrals. In the 1950s it made broadcasts and recordings (with conductors of the stature of Otto Klemperer) and appeared at the Royal Festival Hall and the Wigmore Hall, as well as touring in Europe. Some of these trips were made in connection with the Oecumenical Fellowship of Boys' Choirs in Worship, on whose committee Sidwell sat for a time. The fellowship fostered contacts between boys' choirs all over Europe.
St Clement Danes at the Aldwych reopened in 1958 after the repair of its massive wartime damage, and was designated the church of the RAF. Again, Sidwell was called in to restore a wounded musical tradition. Thus began a Sunday routine which saw him direct the music for matins alternately at Hampstead and St Clement Danes, then take in early evensong at St Clement Danes, before the rush to Hampstead for evensong - preceded by choir practice.
At St Clement Danes, Sidwell received approval for the establishment of a nucleus of eight professional singers - expanded as needed - to cope with a round of duties which included all manner of special RAF occasions, from memorial services and statue unveilings to weddings with an aviation connection. Among his singers were the countertenors James Bowman and Paul Esswood. The BBC regularly broadcast mid-week choral evensongs.
Sidwell's trademark, which has left an indelible impression on all who sang for him, was an iron discipline in the quest for perfection, however elusive that might be. He knew what he wanted, and woe betide the BBC producer who dared to query a point or two shortly before the green light went on. But Sidwell also had a sense of humour which ran to an inexhaustible supply of limericks, not all of which could be repeated in church.
To fill any time left in mid-week, Sidwell founded variously the Hampstead Choral Society (1946), which provided a platform for a host of British oratorio soloists, the smaller-scale Martindale Sidwell Choir (1956) and the London Bach Orchestra (1967), which staged regular concerts under his direction at the Royal Festival Hall and Queen Elizabeth Hall. While he had a love of English and French music, Bach was perhaps closest to his heart. Sidwell's readings of his music were lighter and faster than audiences were used to in the 1950s, but they anticipated the style of early music performance that has since become familiar.
St Clement Danes acquired its own music society in the 1960s under Sidwell's leadership, its concerts being guaranteed sell-outs. A Fellow of the Royal College of Organists, Sidwell continued to give recitals, and was appointed Professor of Organ at his Alma Mater, the Royal Academy, in 1963.
While RAF chaplains at St Clement Danes came and went, it seemed Martindale Sidwell would go on forever. He was still juggling duties at his two churches until 1992. When he retired, at the age of 76, he found pleasure in taking a seat in both sets of pews Sunday by Sunday, followed in the case of St Clement Danes with, as ever, lunch and a drink or two with his friends in the pub across the road.
John William Martindale Sidwell, organist, choirmaster and conductor: born Little Packington, Warwickshire 23 February 1916; Organist and Choirmaster, Hampstead Parish Church 1945-92; Organist and Director of Music, St Clement Danes 1957-92; married 1944 Barbara Hill (two sons); died London 20 February 1998.