I happen to be restoring a Frazer Nash F.N.5 front turret from a Lancaster. One of the few items I'm missing is a cupola! It doesn't need to be glazed (I'm resigned to having to produce new perspex at some stage) but the frame work would be extremely useful, even if it turns out not to be from a Lancaster (the F.N. 5 was used on the Wellington, Warwick and Stirling, too).
I hope you'll consider my request!
Regards
Al