Hugo ran "The World of Cryton". There appear, at this point, to have been less than a dozen ARCBBSes run in total. At least one of them (The Arcade BBS at http://www.arcade.demon.co.uk/) is still running. (link points to archive.org copy of the site)

"My arcbbs was the first multi-user system on acorns; one site ran with 16 lines I think, though 8 of these were telnet connections. I don't think there were more than 30 copies of arcbbs ever sold, but about 15 active BBSes sounds right." - Hugo Fiennes