Hi All, Not a plumber but pretty handy with tools and experienced DIYer, however have come across a 'good one' that I am struggling with and wondered if someone would be able to provide some help. I have a 1930's house and a set of radiators with what seem to be very odd tails on them. I need to remove the rads to decorate and the valve are leaking (1st problem) which means I need to replace them with a compatible thread patterned thermostatic valve (2nd problem) I have been to a few plumbing centers and everyone I have spoken to says radiator tails are only one of two sized 1/2" or 3/4" so they have sold me the cap end nuts to stop the leaking while decorating, so I can replace the valves when I find the correct size. I have taken a few measurements and can uploads some pictures if needs be. Thread width = 21.5mm Thread spacing (peak to peak) = 1mm Parallel Thread If anyone could help me with what this may be it would be greatly appreciated!