Messrs Butcher, Baker, Carpenter and Plumber are currently attending another convention. No-one is currently, nor ever has been in the same profession as their name and no-one has had the same profession twice. Alan is now a butcher, whereas Mr Brian Butcher used to be a baker. The person who is now a carpenter used to be a butcher. Charlie has never been a baker, Mr Darren Carpenter has never been a butcher and Mr Baker is not now a carpenter. Can you determine their full names, along with their current and previous professions?