Rosevidney1: here is a picture of a Lancaster I (FE) of 207 Squadron (The Aeroplane photograph in Aircraft of the Royal Air Force by Owen Thetford, in which the photo of the white Mk VII marked "9X" (20 MU) also appears (Blacksheep's post)). This I (FE) has similar markings to the feathered friend in post 1, but it does have turret guns.
Laurence