sycamore,
You're wrong and I'll give a clue why. I took the photo yesterday at the Aerospace Museum in Calgary - no Halifaxes there.
Kitbag is correct. It's a Lancaster Mk X., FM136:
I had wandered around to the tail after I noticed that the rudder trim tabs had external mass balances, which surprised me. I then had a look in the turret and now have even more respect for the poor sods who had to sit in that cramped little space, in the cold, peering into the darkness for nightfighters. I read that the gunners often took out the perspex that I took my photo through, in order to have a better view!
The turret doors were open and I realized I could see all the way to the cockpit.
Kitbag has control.