The pump on the R50 is run by an electric motor not the usual pulley on the engine. As you say, later MINIs have an electric motor on the column. My Haynes mentions the motor pump but almost nothing else about it. There is also an electriic cooling fan for the pump and fluid.
Good - Fast - Cheap: Pick any two.
E23 735i; E30 318i; E32 735iL (X 2 - 1 White and 1 Light Blue); E34 535i; E38 735iL; R50 Cooper; R55 Cooper Clubman.
E21 318i; E32 735iL; E34 535i; E38 730iL; E53 4.4i