'A' is a Stone-Faiveley single arm pantograph, widely used on multiple units. is the GEC/AEI cross-arm type used on some of the 25kV ac locomotives.
'B' is the Faiveley design used on some early locomotives (this had a substantial frame of one inch tubular metal and hence is sometimes called the 'bicycle frame type').
'C' is the GEC/AEI cross-arm pantograph
'D'...
more... is the BR/Brecknell, Willis Pantograph developed in the early 1970s, this became the standard for high speed locomotives in the UK (and in several other countries). This design of high speed pantograph was first geared to run at 110mph and subsequently has been widely used by several countries as well