Thanks to all contributors!
Same fault as above - no wipers on the column switch, blowers and wipers on the blower switch!
Decided to cut black wire and put in new earth to the motor, worked like a charm. Then found blower wasn't working! Connected the now defunct earth (from loom) to the new earth - bingo!
Who designed this wiring circuit, suggests I had another fault on the blower circuit. Strange how the connection appeared to support the blower but not the wiper motor.
Tom
October 2008