1956 Prototype Tube Stock - Detail Differences

[DustyBin]

I believe there were three seven car (strictly speaking 4+3) trains of 1956 stock with one each built by Metro-Cammell, Birmingham RC&W and Gloucester RC&W. They had long service lives, especially considering they were non-standard (to an extent) but I can't find much information on them. I'm particularly interested in any detail differences between the three. I've found photographs of these trains showing two different cab roof treatments so it's safe to presume they are from two different builders, but which two I have no idea. Can anybody explain how to identify each of the three builder's trains? Photographs would be even better!

Thanks.

 

[Dstock7080]

Gloucester RC&W 1008-2008-9009-1009+1010-2010-1011, flat rainstrips over doors, beading line under side windows

Birmingham RC&W 1004-2004-9005-1005+1006-2006-1007, curved rainstrips over doors, no side beading line

Metro-Cammell 1000-2000-9001-1001+1002-2002-1003, curved rainstrips over doors, same cab roof as production 1959/1962 Stock

 

[DustyBin]

Gloucester RC&W 1008-2008-9009-1009+1010-2010-1011, flat rainstrips over doors, beading line under side windows

Birmingham RC&W 1004-2004-9005-1005+1006-2006-1007, curved rainstrips over doors, no side beading line

Metro-Cammell 1000-2000-9001-1001+1002-2002-1003, curved rainstrips over doors, same cab roof as production 1959/1962 Stock

That’s a very comprehensive reply! Much appreciated, thank you.