In reply to johnj:
You're right. Bit stupid of me really, of course that's what to do.
To the other posters suggesting that my wheel is u/s or fatigued, are we saying that Ridgeback will have sent out a substandard wheel? Possible I accept, but it did a reasonable season training for the Trossachs Ton last year, as well as the ride, with just one breakage on the shocking Stronachlachar to Aberfoyle road.
Since then, I have upped my speed and distances, but still carry a fair bit of weight (95kg), so I think it's that set against modern bikes having fewer spokes (32 rather than 40 on the rear according to Sheldon Brown) and the crappy state of the roads.
Bloody hope I don't need a new wheel, as funds are tight, and the damn thing cost me enough.