Underwood left school at 16 to work with Jet Harris, and joined a tour of Britain with Sam Cooke and Little Richard.

It was at the end of this tour that Screaming Lord Sutch (in whose band, The Savages, Blackmore now played) suggested he approach the independent record producer Joe Meek for further session work.

"Satan's Holiday" was a fast, rock adaptation of Grieg's "In the Hall of the Mountain King", a tune that stayed in Blackmore's stage repertory right into the 1990s.

With The Herd, Underwood began playing at all the major venues on the circuit, such as the Marquee Club and Eel Pie Island.

However, a year later he accepted an invitation from singer James Royal as a session drummer for a two-week residency at Hatchets in London's West End.

At the end of the residency, Underwood decided to stay with the band, the James Royal Set to tour with Johnny Cash.

Undeterred, Grant went on to recruit two previously unknown musicians, the singer Robert Plant and drummer John Bonham, and the band became Led Zeppelin.

Underwood joined ex-The Authentics frontman Henry Turtle in psychedelic rock outfit The Doves from 1967 to 1968 alongside former The Herd guitarist Terry Clark plus Brian Curtis, Ian McGlynn, and Harvey Hinsley (formerly of The Outlaws and later a member of Hot Chocolate.

Despite numerous BBC sessions and two singles, commercial success never came for the band and there was a feeling that they were failing to move with the times as the music scene rapidly changed at the close of the 1960s.

Along with Jon Lord, Blackmore attended an Episode Six gig to listen to Gillan, and shortly afterwards recruited both him and Roger Glover into Deep Purple.

After several showcase gigs, Quatermass were signed by George Martin's Air London company and began to put together their first album, using their own material plus several songs written by Steve Hammond.

Despite wide critical acclaim, the project had insufficient financial backing however, and there were many problems on their subsequent tour of the United States.

Former Deep Purple drummer Ian Paice had also auditioned for Gillan but according to guitarist Bernie Torme "...he had some difficulty after playing "Secret of the Dance" due to his only having one lung, and being a bit out of practice.

In 2006, Underwood along with bassist Johnny Heywood and former Heavy Metal Kids guitarist Cosmo Verrico formed the band Raw Glory, who released an album, City Life in 2007.

A memorial concert for Mick Underwood was arranged at The Cavern in Raynes Park, London on 18 April 2025, featuring members of his former bands, with all proceeds going to charity.