I've seen Hawkwind more than any other band over the years, what with one thing and another, and saw HLL's solo band as well. So much of what the Hawkwind ethereal sound was came from his guitar, it was practically defining.
The Hawkwind website said his passing was peaceful, and I hope his Rest is as well.
The first time I saw them live, in 1984 I think, he was part of the core line-up, so he's in my 'first impression' of them forever. That's one of the entertaining things about Hawkwind - practically every gig had a different line-up!
Quick google tells me it was March 18th, the Earth Ritual Preview Tour.