
This scandalous regeneration of the Music Master was limited to the UK market in 1965 when Harry Chamberlin took legal action against Steely Electronics, who had based it heavily upon one of the two Music Masters that arrived on the boat from America with the elusive Bill Franson. This limitation to the UK market corresponds with the Mellotron’s eminent place in the British prog-rock sound of the 60s and 70s. One of the original Chamberlin 600s that had arrived with Bill Franson would eventually find its way into the studio of Todd Rundgren and feature heavily XTC’s Skylarkin album.

The internal tapes feature three pre-recorded samples: the flute - most notable in the intro of The Beatles' "Strawberry Fields Forever" - a cello and a string section. Each time a note is played on the keyboard a rubber pinch roller sets the length of tape to a rolling capstan. As the tape plays the pinch roller motions the tape towards a playback head. It can take up to 8 seconds for the tape to reach the playback head at which point the sample stops. When the key is released a spring winds the tape back to the play position within half a second.
In 1967 the BBC purchased a mark II Mellotron and loaded it with special effects tapes. These effects would be heard on Dr. Who programmes for a number of years.

Notable examples of the Mellotron in motion: The Beatles - Strawberry Fields Forever
David Bowie - Space Oddity