The Invasion was an eight-part Doctor Who story made and transmitted in 1968. Written by Derrick Sherwin (from a story by Kit Pedler), it starred Patrick Troughton as the second Doctor and featured the Brigadier, UNIT, and the Cybermen in a “modern Earth invasion” Doctor Who story that became a hugely influential series at the time. At the helm was Douglas Camfield, one of popular television’s most maverick and talented directors of the 1960s and 1970s.

The music was composed by Don Harper, the third Australian émigré composer (after Ron Grainer and Dudley Simpson) to work on the programme. Harper’s soundtrack may have been influenced by John Barry’s score for The Ipcress File (1965). He uses the cimbalom in the score, and the artist was most likely John Leach (a.k.a. Janos Lehar), who played on The Ipcress File, King Rat and The Persuaders.
The release also features “Muzak” by John Baker (referred to as such in the cue sheets for episodes 1 and 2), which had its first outing in an Out of the Unknown episode.

The master tape of the music for ‘The Invasion’ was lost soon after transmission, but Harper retained a 7½ ips ‘composer’s copy’ that forms the basis of this release. Additionally, the score was augmented by extensive use of electronic sounds by Brian Hodgson of the BBC Radiophonic Workshop.