He was an early user and promoter of the Mellotron, a tape-based sampling keyboard, and co-wrote the theme music for the first On the Buses film.
[2] He studied at a branch of the London College of Music in Liverpool and started playing in variety theatre in 1947.
[3] By 1962, he was working in The Magic Carpet Inn in Chelsea, London, where he was spotted by big band leader Eric Robinson and television personality and magician David Nixon.
[4] He featured on a ten-minute promotional film made by Pathé that was regularly shown in cinemas[5] and appeared on the children's television show Blue Peter, demonstrating the Mellotron to Valerie Singleton.
[7] Unwin left Mellotronics in 1969 and started working for EMI as an A&R man and producer,[8] where he composed the music for the first film version of On The Buses,[2] including co-writing the theme tune with Roger Ferris.