Have a look at this article on a famed example of the 247D, DZ203, the first aircraft to make a completely blind landing. The first image is the aircraft during its flights with the RAF, which places it after 1942. Note the reverse-slope windows that are a hallmark of the early 247's.

However, this is a D model, and the D model of the 247 is noted as having had these removed and replaced with normal slope-down windows. This can be seen in the images of the other 247Ds on the same page, which were produced in the same batch of aircraft.

Does anyone know what's going on here? Were certain batches one way or the other?

NOTE: No, this is NOT a dup. The original answer from a while back states that all 247D's had forward slope windows, but this example clearly does not.