Well, I guess I know where I am now after the investigations and help here.
A short circuit on the right hand side.
I expect I shall just have to work through every wire and connector on the right side and see if I can find the issue.
Wear is unlikely as the bike has a genuine 150 miles on the clock.
Well, I have disconnected the rear light connector. Bypassed the blinker relay.
The short circuit is still happening. The left indicator comes on but the short circuit still happens on right.
If I disconnect the black and green wire behind the headlight the short circuit stops.
On investigation of the wires back to the middle I don't find anything obvious.