She did not see the engine fall away but it was described to me that it fell into a flooded gravel pit about a mile from their house, in the area of Thorpe Park and the M25/M3 junction nowadays.
I recall a member of the public being quoted that the pilot was fantastic, he jettisoned the engine so that it fell into the gravel pit and avoided the populated area.
On that day I was based in a building a few feet from the peri track under 28R approach.
A VC10 did a very late aborted landing over us and we ran out to see it but were then confronted with the scene of the 707 on fire.
A very sad day.