Small side windows in Lancaster

[Grexx]

Hi all,
On many Lancaster photographs you can see the row of small rectangular windows with rounded sides placed on both sides of fuselage above the wings and between the cabin and mi-upper gun turret.
Normally in most cases they seem to be painted over in black but sometimes they were left intact when the line dividing the black and upper brown/green camouflage was a little lower than the line of those windows.
Were they ordinary small perspex windows which alloweed to make air observations from inside the aircraft? Or pehaps there was another reason to place them there.
Were they typical for all production batches from factories in UK?

[jonheyworth]

They are just windows to light the fuselage interior . Usually painted over

[Chas]

The windows were discontinued in later models. I'm not sure exactly when the change occurred -- early 1944, I guess.

[JDCAVE]

Photos I have confirm that Canadian built Lancasters KB.712 and KB.721 had these windows. KB.762 and KB.865 did not.

Jim