As a member of 99 Sqn I attended the Paris Air Show at Le Bourget in May 1961 and witnessed "Doddy" Hay of Martin Baker making a 'live' ejection from the back of a lorry. He was a very brave man. He ejected, parachute opened and landed safely.
I thought he ejected from a moving lorry as it raced along the runway, but after 53-years my memory is not as it was as the event was reported by Flight Magazine as from a stationary lorry, which is even more bonkers, but that's how technological advances are made.
As reported in Flight.
Martin Baker – Paris 1961 — Flight Magazine 25th May 1961
Perhaps the most interesting exhibit will be the prototype rocket assisted ejection seat which Martin-Baker hope to have on display. This rocket seat will have zero-speed/zero-altitude capability and is especially suited to VTOL aircraft. During the flying programme at Le Bourget on June 3 and 4 it is hoped to demonstrate the capabilities of this seat from a ground rig mounted on a lorry and using a dummy subject.
Flight Magazine 8th June 1961
By no means all the participants were fixed-wing aeroplanes. There were both helicopters and parachutists, one of the latter being W. T. H. Hay of Martin-Baker, who made a dramatic rocket ejection from a stationary lorry. This was the first public demonstration of Martin-Baker’s newest ground-level ejection equipment, which shot Mr Hay about 300ft into the air. On the Saturday, owing to a crosswind, he unfortunately landed on the edge of the runway instead of on the grass.