My money would be on Leeds. Hunslet, Hudswell Clarke, Manning Wardle and Fowlers all across the road from each other, plus Kitsons. The other possibility would be Glasgow - North British, Neilsons, Dubs, and no doubt others I've forgotten.
Given the rate at which they all amalgamated with each other you could have a job for life trying to tot them up. Don Townsley filled a very large (and very good) book* on Hunslet alone. From the beginning in Leeds you've got Murray, Fenton & Wood; Murray, Fenton & Jackson; Todd, Kitson & Laird; Laird, Kitson & Co; Kitson, Thompson & Hewitson; Kitson & Co; Harthorn, Davy & Co; Shephard & Todd; E.B Wilson & Co; Wilson & Craven and we aren't even up to 1860 yet !
*The Hunslet Engine Co - Over a Century and a Half of Locomotive Building - Don Townsley, PLateway Press, 1998
Given the rate at which they all amalgamated with each other you could have a job for life trying to tot them up. Don Townsley filled a very large (and very good) book* on Hunslet alone. From the beginning in Leeds you've got Murray, Fenton & Wood; Murray, Fenton & Jackson; Todd, Kitson & Laird; Laird, Kitson & Co; Kitson, Thompson & Hewitson; Kitson & Co; Harthorn, Davy & Co; Shephard & Todd; E.B Wilson & Co; Wilson & Craven and we aren't even up to 1860 yet !
*The Hunslet Engine Co - Over a Century and a Half of Locomotive Building - Don Townsley, PLateway Press, 1998