Lancaster PB669

[Hanglands]

Hello,

This is one of a few pieces of wreckage I came across recently. They are reportedly from Lancaster PB669.



This one piece in the photograph is something I can't identify, and it has no markings that I can see. Its almost half an inch thick, and looks to me as though it could be some sort of bracket. Any ideas?
The other pieces include parts of the oxygen supply, and bare part numbers and AM stamps.

So I started trying to find out information on PB669.

This is what I have read :
The aircraft was 'borrowed' (where from?) by 156 Squadron PFF and took off from Warboys on a training flight at 1040hrs on 11/03/45. Weather and visibility were good, with a sheet of Strato Cumulus with a base of 4000ft.
At 1248hrs, PB669 contacted base with nothing to report.
At 1310hrs PB669 nose dived with full power between Spaldwick and Molesworth, approximately 12.5 miles south west of Warboys. All crew were killed.

For this flight PB669 had an eight man crew (two Navigators), which were exclusively RAFVR :
Pilot F/Lt AC Diemer MiD
Nav. F/Lt Brenard C. Brooker DFC+ (previously of 35 Sqdn)
Nav. F/Lt AM Stewart
Flight Eng. Sgt KL Pile DFM (previously of 166 Sqdn)
Obs. F/Lt J Robertson DFM (previously of 97 Sqdn)
W/Op F/O CA Robson
AG F/Sgt DW Kidd
AG W/O S Oldfield

The wreck was excavated in 1994.

And thats about all the info I have so far. Can anybody add to that? I'd like to identify the part in the photo. I'd also like to know what sort of training excercise this was, I guess having two navigators is related to the purpose of the exercise. Also, how could it be known if the aircraft was in a power 'on' dive? And which Squadron was the aircraft borrowed from?
Many thanks to anyone with any further information.

Regards,

H.