It's all academic, of course, but it's a shame someone in the RISC OS community didn't acquire the Acorn trademark rights before the naff PC laptop me-too vendors did. Acorn may have been a 'dead' and failed company, but at least there was brand awareness there, particularly with British computer industry veterans. Perhaps the rights were too expensive or perhaps no-one thought it was a good idea.
My remark was because calling an event 'Acorn World' seems naive given that another (possibly unfriendly) organisation is now actively using the brand. I hope it doesn't become a magnet for solicitors' letters!
Seriously, though, I do hope your event is a success. In particular it's a testament to the BBC Micro and its remarkable longevity that people are still talking about it!