Yes, I've heard of them. It was a father-and-son business that produced swaging gear of the very highest quality, and commensurate pricing. I recall that their Whitworth die set [punch and swaging die] was almost £500, without the hydraulic pump gear, back then. When the father died, around 2010, the son carried on for a short while, but finally gave up the ghost. Over in the USA there is Dave Corbin, who supplied many of the Latham's bits of kit.
For sure, swaging is a very useful way to make otherwise unobtainable bullets if you don't want to go casting, but by golly, it's dear. The complete (spare) Whitworth set-up from Dave Corbin was mine for a special price of just $3000.
IMO your very best bet is to get a custom mould from Jeff Tanner - excellent quality, VERY fast turnaround, and he's right here in UK. Figure around £50 - 60 for your custom mould, and less than two weeks. His website has recently had a title change - something like bulletmould.....take a look.