Bang on the money again v8 (offside wing) - and resistor is 100% ok too.....
After much multimetering, we (i.e. my mate who knows what he's doing....) traced a complete power loss under any load between the under seat mega fuse and the steering column switch. 12v max at switch dropping to 8v or even nil under any load - even the side lights.
Traced the spur of the same feed to the resistor for the dim dip, and no fault at all 12.4v+. So, new feed off that circuit before the resistor, basically just abandoning the faulty wire wherever it may be, and spliced into the connector loom/block in the dash. All beautifully crimped and soldered and taped - Bob is indeed your mother's brother.
Caused some real grief failing entirely coincidental to the injector failure - such is life - now I really can use it night and day till the next bit breaks!! Thanks for the help. A