Mackay grew up in London. He attended Reading University, where he became friends with fellow student Brian Eno. In 1971, he answered an advertisement by Bryan Ferry, who was looking for a keyboard player for his band Roxy Music. Although Mackay played the saxophone and oboe, but he also had a synthesizer and was therefore included in the band. Brian Eno, who actually had no musical training, learning to deal with synthesizers and pushed so also the band. Mackay at the time was also working full-time music teacher at Holland Park Comprehensive School.
Mackay was known at Roxy Music, among others, for his Duck Walk, a tribute to the music of the 1950s, the saxophone solo.
He brought in the 1970's two solo albums on the market and composed the music for the album rock Follies, which peaked in the UK charts in 1976, the No. 1. Mackay also worked with Mott The Hoople, John Cale, Pavlov 's Dog, Godley & Creme, Eddie And The Hot Rods and 801. 1981 he published Electronic Music: The Instruments, The Music & The Musicians.
After Roxy Music disbanded in 1983, Mackay and Roxy Music guitarist Phil Manzanera joined forces to The Explorers. The band recorded an album in 1985, the second album in 1988 appeared under the artist name Manzanera & Mackay. Under this name they recorded two more albums, which included both old material from the Explorers as well as new.
Mackay finally took a 1989 Christmas album with The Players, a band that consisted of English folk musicians on. He also wrote music for British television.
Since 2001 he is touring again with the reunited band Roxy Music.
- In Search of Eddie Riff (1974 )
- Resolving Contradictions (1978 )
- Rock Follies (1976 )
- Rock Follies of '77 (1977 )
Explorers / Manzanera and Mackay
- The Explorers (1985 )
- Crack The Whip (1988 )
- Up In Smoke (1988 )
- The Complete Explorers (2001)
- Christmas (1989 )