8 FTS RAF Swinderby, 1956, I watched a Vampire FB5 taxiing ahead of me start the take off roll, rotate normally and then go into a vertical climb until it stalled at a couple of hundred feet, dropped a wing and crashed in the grass about fifty yards from the side of the runway. They found a spanner in the port boom had jammed the elevator fully up. The spanner was traced back to a Maintenance Unit, but not it's owner.