Ah well, a good reminder to do all the basic checks after a system failure... check cables. It wasn't the PSU that died, it was the fuse in the plug.
Replaced the power cable and it fired up nicely. I turned it off again and promptly went out to PC World to buy another PSU. After nearly assaulting a PC World Till assistant for trying to rob me I decided to leave them alone... he wasn't trying to rob me really, that genuinely was the price of their PSU's... (You did say "at a push" Mr. H, I wasn't suggesting it was your fault.)
Anyway, went to Maplins and bought a CiT 750W jobby for £50.00. If I'd have remembered the £5.00 voucher I got from them for my purchase of some pointless A42CX's recently it would have been cheaper, but that's life.
Now I just need to catch up with some work and I'll be gunnin' with y'all later.

Just be a nutter... life becomes much more exciting, and people won't expect anything more of you...