The son of a Welsh miner, Terry Johns is a french horn player with a distinguished career as a member of the Royal Philharmonic and the London Symphony orchestras, the Barry Tuckwell horn quartet, the Alan Civil horn quartet, and the Jack Brymer wind soloists. He has played with many jazz "greats", including Tubby Hayes, Kenny Wheeler, Stan Getz, Clark Terry, Phil Woods, and John Dankworth.
He is also a composer of music for television and has written music for the RPO and LSO brass. He composed the theme and incidental music for Harlech TV's "The Pretenders". For this he recruited players from the ranks of the RPO, and the LSO, for the studio orchestra led by Sidney Sax, and conducted the sessions himself.
In 1984 the actor Robert Hardy while arranging the memorial service for Richard Burton at the church of St Martin in the fields, invited Terry to arrange the final hymn (Battle Hymn of the republic) for the Rhos Cwm Tawe male voice choir and to compose an obbligato solo trumpet part for Maurice Murphy. The music was completed in a sleeper compartment between Edinburgh and London just hours before the service, with the soloist proof-reading from the top bunk!