I watched a Trident jump the chocks at the LHR BEA base,between the old .hanger blocks.
Phoned for action and a Transit van arrived and out of it jumped some engineering types.
only to see their van on the move due to the wind.so double trouble.
I seem to recall that the Trident was due to be scrapped.
It was a very sheltered site so it must have been a strong gust of wind on a really empty aircraft.