Well, the new problem of the light being on all the time has sorted itself - I found instructions on sensor tests from Jon@work in another thread and unplugged the ABS ECU, checked the ohms across the terminals (which were all correct) and plugged it back in - bingo - light clears itself. Off for a spin now to see if it comes on at speed.

Also noticed that the oild pressure light has stopped coming on. Could be the bulb but is that an MOT item now? If it is, I have the one beside the oil pressure gauge.