I have been looking for something which may not exist in RTW / OTR. What I would like to find is a not-too-expensive detachable collar shirt. I know one can buy these from reproduction companies, and formal 'tuxedo-fronted' or plaque-fronted shirts of course. However, I would also like such a shirt in a fairly slim, modern fit, and in a variety of colours and patterns - i.e. high quality conventional dress shirts to which one can fit collars. The only think I have found so far is a simple white one from Thomas Pink. Most of the usual online shirtmakers do not seem to produce them and even the MTM options do not seem to offer them. A search on this site produced nothing useful. So, does anyone here have a recommendation, or am I just going to have to go fully bespoke to get the collar / shirt combinations I want?