People talk about the Ingles gym but I can only think of 4 world champions they've produced ever- Naseem Hamed, Johnny Nelson, Junior Witter, Kell Brook. Not as many as you'd expect for how much Sky talk about the famous Wincobank gym. Billy Joe Saunders moved there as a world champion so not sure if that counts. Joe Gallagher has had 4 also - Scott Quigg, Callum Smith, Liam Smith, Anthony Crolla (plus Macklin got robbed against Sturm) Enzo Calzalghe 3 Joe Calzaghe, Enzo Maccirinelli, Gavin Rees. And they were all champs at the same time. Peter Fury - Tyson Fury, Savannah Marshall Rob Mccracken - Carl Froch, Anthony Joshua Shane McGuigan - Carl Frampton, George Groves Who else/ who've I missed?
Don't forget my guys Jimmy & Mark Tibbs. Jimmy was virtually involved in some capacity (either cutman or trainer) with most of the best British fighters of the 90s, including Nigel Benn. Mark Tibbs has worked with Kevin Mitchell, BJS, Dillian Whyte and a few other domestic contenders. Also, shout out to Jim McDonnell. Trained James DeGale & Danny Williams. And not sure if Don Charles has trained anyone close to World Title level, other than Chisora, but he's a decent British-based trainer.
All names in the debate, but I suspect no one comes close to Charles Atkinson, who trained numerous world title holders, and is most famously associated with John Conteh, ironically as a promoter rather than trainer.
Terry Lawless. Hope Magri Bruno Stracey also, Jimmy Flint, John Gardner, Jimmy Batten, Bunny Sterling, and loads more.
Shane McGuigan is only 32 - 33 years old and has already won world titles with Frampton, Groves and Taylor - not too shabby is it !! He also has Okolie in line for a shot which could make 4.
Hamed, Nelson and Brook all laced gloves on as children for the first time at the Ingle gym and were developed into world champions which makes it quite unique. Witter spent his entire pro career there. Paul Jones spent many years there before becoming world champion. Considering your obsession with that gym I'm surprised you omitted Nicola Adams. Galahad is another who started there as a child and suffered a bad decision against Warrington but is mandatory again with a title shot due. Liam Williams is mandatory and due a title shot soon.