Thanks Peter,

So if that flap uses a pneumatic ram then it seems to tally with the description of Mod. 1198. The April 1943 pilot’s notes talk about the carb heat being hydraulically controlled, (as do the MkX notes), so I’m trying to understand how this flap fits in with all that and ultimately whether this was a flap fitted to early Lancasters or whether it was introduced in late 1943. I’ve been trying to find some early Lanc photos of this area but as you can imagine, it’s not the most obvious place to stand when photographing them!