It's interesting (to me) that it has a flat windscreen. My Dad's M type (UW 5990... 2M 0715) had one but when the car was restored it was fitted with a split screen - presumably because it was considered more authentic. I have read an original road test carried out on an M type with a flat screen so were they a factory option? Just interested.
As a footnote to the comments by John James about Bader's car being modified, I have a copy of the Daily Express from 15th July 1940 which states that Bader....."had his car adapted". John