actually I'm sure BMI do have a base at BHD....
They have their own ground staff, flight/cabin crew and aircraft at BHD. If that doesn't make it a base what the hell does???
I was trying to justify that there are bases/stations, whatever you want to call them, were only 1 aircraft is based. Now obviously if an aircraft is parked over night (or 2 during the summer at BHD this year) then the crew would also have to be based there. (I don't actually think the crewless aircraft is in mainstream yet, if it was then that would be Ryanairs fleet by now). Another example would be when KLM/Sabena night stopped at BFS, I don't think BFS was classified as a base for them (I could be wrong). Now I don't know if they would have had a back-up crew in those days but they could well have done. A base to me would imply several aircraft parked over night, with full back-up services, several routes etc.