Neil:
If you have access to magzine back issues Aeroplane Monthly Dec 1989 has a very detailed article on the Bombay.
Surprisingly there were only 50 made plus 100 or so similar HP Harrows, miniscule quantities by war standards, yet both types pretty much made it all through WW2 being useful all the way. It would seem that in 1939 the RAF should have had a lot more of them (and perhaps a lot less Fairey Battles)
Regards
Bill