As a member of 99 Sqn I attended the Paris Air Show at Le Bourget in May 1961.
One of the exhibitors was Martin Baker and their demonstration included a 'live' ejection by "Doddy" Hayes from the back of a lorry as it raced down the runway. He ejected, parachute opened and landed safely.
Flight International's report about the show say he ejected from a static lorry, but my recollection was that the lorry was moving down the runway. Either way a very brave man and not something I would do!