The 'Bromwich' name is Tom Bromwich of Coventry, a traditional road frame builder of some age[!] who sold the 'Bromwich' name to Jim McIlwaine who carried on building traditional road and tour frames and then produced the MTB frames in a small number.
The design was an amalgamation of experiment and ideas from the members of our local MTB club bitd. A lad called Sean MacConamara did a lot of racing on them and a number of the club members had custom built Bromwich frames. Not sure how many were built originally though, but not that many. They were all hand fillet brazed in 531 or Columbus tubing I think.
The club was called '12inch plus' btw!! Referring of course to the desired BB height of at least a foot off Terra Firma!!
Tom Bromwich used to visit John Atkins shop when I worked there in the late '90s, he was a good old character
I service and restore Pace forks