Witness unfortunatley (not on airfield but on Downs walking about a mile away waiting to see the Vulcan)
Aircraft arrived, pulled up rolled over the top. Thought bit low for that bearing in mind the downs.
Held the vertical descent probably looking at crowd line, then pulled slowly, realised he was a bit low and REALLY pulled into a quite high alpha. Looked away at that point realising what was going to happen.
POSSIBLY Heard the canopy and seat fire (seen/heard ejection seats before and the sharp crack/whoosh is recognisable) followed almost immediately by the impact. Looked back and HUGE fireball spreading across the landscape.
Just to point out the usual accident interpretations someone else commented (not to me) aircraft was on fire before impact. Im pretty sure it wasnt.