Just wanted to share a few more details re my experience with my choice of couplings ...
Being out of the hobby for so long (30 years plus) and with all the information now available thanks to the 'Web' I settled on the Sprat & Winkle coupling, I very quickly leaned that a jig is a MUST for these to work first time every time - which they will. A lot of people using these couplings dedicate a 'master' wagon or the like which they set coupling height against .. I found the use of a dedicated jig from day one was the way to go, I made the jig from one half of a track cutting aid that I had from the 1980's. All my subsequent stock was fitted with couplings using this jig, and the fact that this jig had slots in for OO track to sit in meant that I could slide the jig over a magnet to test uncoupling and perfect alignment. The first two pictures show the jig itself and the third shows it in use against a newly built wagon awaiting paint.