As above trousers for sale. Only worn a few times - waaayy too big for me! Cock-up with size selection. Cost £hundreds, looking for £125. Comes with braces. PM me if you want any further information.
Euro to UK conversion is 50 to 40. I'm 32" waist and they're too big. I tried wearing them over jeans during the winter (with liner fitted) but I think they're really designed to be worn over skiddies or perhaps a base layer. My guess is they would fit 36" waist up to (maybe) 40". At the end of the day it's all about trying them on I guess. Could come to some sensible arrangement for a genuinely interested person.
18m ago they would have fitted no problem, no so sure now What part of Glos'shire are you? I'm just south of Gloucester