Have you tried on UKAR?

http://forums.airshows.co.uk/

A lot of the photographers on there also upload onto Airliners.net. You can contact the photographers directly.

http://www.airliners.net/photo/Canadian-Warplane-Heritage/Avro-683-Lancaster/2511283/L

http://www.airliners.net/photo/Canadian-Warplane-Heritage/Avro-683-Lancaster/2511253/L

http://www.airliners.net/photo/Canadian-Warplane-Heritage/Avro-683-Lancaster/2499980/L/