Hi Richard,
I believe it is clearly the profile of a Lancaster.
Pointers:
1. the aircraft appears to have four-engines. The vibration of the photographing aircraft, combined with a slowish shutter speed of the camera and the brightness of the cloud/haze below has meant that the engines don't record all that clearly in the image. The shadows all all
four engines can be made out, with the port-inner the clearest, followed by the starboard-inner and port outer. The starboard-outer is only just visible.
2. The wing profile is that of a Lancaster. The inner engines are at the correct point on the wing - i.e. the wing leading and trailing edges converge just outward of the two inner engines, and the wing tip is rounded.
3. The horizontal stabiliser profile is that of a Lancaster. Notice the forward-swept angle of the tailing edge of the elevators, and the slight angle of the leading edge of the stabilisers. The outer tips of the stabilisers are flat and conceivably connect to the vertical fins.
4. the bulge of the rear turret can be made out.
Cheers
Rod
PS - following is a profile from the web of the Lancaster:
http://d951443.u114.weberz.com/image...le_drawing.JPG