Well, the 6 point ring spanner did the trick, albeit with the square end of a 1/2" extension bar in the jaws of the spanner for extra leverage.
On removing the disc/drum, all seemed well - no broken springs, locating pins in place, shoes not worn excessively.
Then to my embarrassment, I could see that I had been moving the adjusting wheel the wrong way!
Its up and over!
Anyway, handbrake seems ok on the third click although I've yet to test it out on a hill.
So I've learned a lot during the this episode, not least the helpfulness and patience of folks on this forum.
Thanks again everybody,
Malc