So much influence!!!
But to strip it to the bare bones...
Chronologically for me (and what they influenced for me)...

Them there Beatles...
plus a whole myriad of 'sixties' artists! - first interest in music as a whole!
Ian Anderson (Tull) - songwriting/vocals/material/style!!
Martin Barre (Tull) - elec gtr playing
Andy Powell (Wishbone Ash)- elec gtr playing
Andy Latimer (Camel)- elec gtr playing
Steeleye Span - engendered my interest in the tradition
Fairport Convention - engendered my interest in the tradition
Martin Carthy - acoustic guitar playing / engendered my interest in the tradition
Nic Jones - acoustic guitar playing / engendered my interest in the tradition
Richard Thompson - songwriting / acoustic gtr playing
Keith Hinchliffe- acoustic guitar playing
Stephen Fellowes (Comsat Angels)- songwriting
(those last two from the parish of Sheffield!)