He attended the Alpha Boys School under the tutelage of Vincent Tulloch, while playing with Joe Harriott (a lifelong friend who considered McNair his de facto younger brother), Wilton "Bogey" Gaynair, and Baba Motta's band.
Once in London, he quickly gained a reputation as a formidable player on flute, alto and tenor saxophone, leading to a regular gig at Ronnie Scott's Jazz Club.
The session saw him team up with Ornette Coleman's then current rhythm section of David Izenzon (bass) and Charles Moffett (drums), for a set of standards played with hard swinging intensity.
His next (self-titled) album, cut for RCA in 1968, recorded at Trident Studios featured probably his best known composition, "The Hipster", which was included on Gilles Peterson's 2004 Impressed Vol.
Recordings as a jazz sideman included sessions with the jazz-rock/big band ensemble Ginger Baker's Air Force and John Cameron's Off Centre.
He recorded with visiting Americans Jon Hendricks, pianist/vocalist Blossom Dearie and drummer Philly Joe Jones and performed with saxophonist Eddie "Lockjaw" Davis at the Manchester Sports Guild in 1967.
His flute was featured on the soundtrack for Ken Loach's film Kes (1969), with music written by regular McNair collaborator John Cameron.
Throughout the late 1960s he also played on many other jazz-inflected folk music and progressive rock albums, including John Martyn's The Tumbler and Davy Graham's Large as Life and Twice as Natural.