I think it has something to do with the industrialisation of the razor (and cutlery) industry in Germany (specifically Solingen) in the early 20th century, which may have caused the Sheffield cutlery to bleed out slowly. It didn't eradicate it, but it must have made it more difficult for Sheffield cutlers to keep up. That's my guess. There probably aren't many able razor grinders left in Sheffield that have any access to or interest in picking up business. Even in Solingen there are only a few handful of skilled Meisters left, and they're getting old fast. One drop forge, 15 or so ageing Masters...it doesn't look too bright.