If the cine film could be found, perhaps a more accurate assessment of the flypast speed could be made. 'Witness estimates' at air shows are notoriously unreliable.
The original Mk 1 had a substantial altimeter position error at approach speeds; did VX770 have similar errors at higher speeds? And on what altimter setting was the '250 ft' flown? I other words, it cannot be certain that the height of the flypast was a deliberate contravention of the flight authorisation.
Was the aircraft really within less than one wingspan of the runway?
Vulcan VX770 was a hybrid; it was the original first prototype which had ultimately been fitted with Conway engines at Hucknall for engine development testing. It lacked the strength of the Mk1 and with lower structural weight and around 70000 lb of thrust compared to the original 26000 lb of thrust, it would have been a very 'hot ship' indeed. But the most serious issue is that RAF and company test pilots had routinely been flying wholly unnecessary aerobatics in the aircraft; it had often been rolled, and, on at least one occasion, it had actually been looped. A fact that had been covered up and probably wasn't made known to the crash investigators. Rolls-off-the-top had also been flown, so it is highly likely that the aircraft had been substantially damaged by other pilots before the Syerston crash.
In those days, there was intense competition between aircraft companies and each would try to outdo the other. So the practice of flying wholly pointless and potentially seriously damaging aerobatics in medium bombers such as the Vulcan would not have raised many eyebrows.
Even if the display pilot exceeded his brief - and do we really know that - the most likely cause of the accident, to my mind, was the damage inflicted by the irresponsible flying of other pilots.
Some years ago, we had more fuel leaks than normal in one of our VC10K3s. After a bit of delving, and looking at fatigue records, it was evident that one pilot (whose enthusiasm was not matched by his flying ability) had flown at least 3 fast flypasts at high weight with high 'g' (for a VC10) into a climbout. One departure from Abbotsford with over 80 tonnes of fuel on board had included a 300 KIAS flypast in slight turbulence, then a ham fisted yug into a climb. That single flypast put over a year's worth of fatigue on the aeroplane.....