While attending art college together in 1964 Gardner and Wood met Tony Munroe, Ali McKenzie and Pete McDaniels and formed The Thunderbirds.
In 1967, Gardner recorded some tracks with Jon Lord, Ronnie Wood and Twink under the name Santa Barbara Machine Head, released on Blues Anytime Vol.
In 1973, while recording an album with Jackie Lomax and George Harrison in New Orleans, Gardner met his future wife, Paula, a successful entrepreneur in the clothing business.
In 1974 Gardner joined Badger as bassist, a group featuring Jackie Lomax on vocals with drummer Roy Dyke and keyboardist Tony Kaye (formerly of Yes) and guitarist Paul Pilnick (formerly of Stealers Wheel).
In the mid 1980s Gardner was a member of Ian Wallace's Tea Bags group with Jackie Lomax, David Mansfield, Peter Banks and Graham Bell.
There are several prominent guests featured on these recordings including Carmine Appice, Bruce Gary, Mick Taylor, Jackie Lomax, Brian Auger and Ivan Neville.