This firm do a pretty good line in bits and pieces for antique Triumphs. Relatively cheap and speedy delivery. http://www.feked.com/
Crikey Sceptic reading the thread title and being a Golden Oldie myself I thought great this thread must be about false teeth, replacement knees or even incontinent wear Dave.
Living nearby I use Fecked for bits for my BSA, often have interesting bikes for sale in addition to parts. Bonus is the nice bends to get there.
"Rockerbox" Its in Wrecclesham, Surrey. Run by a couple of hairy old bikers and all they do is fix up old triumphs. Worth a visit
Been down there a couple of times, good old school guys, willing to chat give advice etc etc but very busy, when enquired if I wanted any work on my tbird done when could they fit it in he politely laughed and showed me the bikes lined up awaiting their attention! That was a couple of years ago tho.