The Harrier incident at Yeovilton was in 1975. I was sitting on the wing of one of our 'Poachers' aircraft which was across the pan from it when it went off. It happened so quickly, not a nice thing to see.
I also saw it (from the crowd). The pilot completed his display, taxied in and shutdown normally, then put the canopy back and unstrapped. The seat went off as he stood up on the seat , holding the windscreen frame. I always wondered whether he was distracted by the lack of a proper ladder.
I was always fascinated by the various ingenious methods that pilots had to employ to gain access to their cockpits at Yeovilton - notably F104 pilots climbing up the wing from the tip then straddling the fuselage to get to the cockpit!