Got some help from an electrical retailers who sold me a new reg. with new bushes for a tenner.
Told me to check earth strap and bridge +ive and -ive terminals on the alt. to check if the wiring to the battery light on the dash had corroded a bit. When I did this got 13.5V on idle. Turns out the connector to the dash clocks was loose - not telling the regulator to kick in.
The bloke even took the regulator back!!!!
All in all a good result