I'm sure this question comes up a lot and you guys must be a little sick of answering it but I'm a little unsure of my options.

I was previously a regular traveller to the US and Japan and I've always travelled on Virgin (VS) previously. I'm a silver member of their FF program but due to changes in projects and role I don't seem to be flying them much anymore.

My company is very cost centric so I generally always fly economy and I have very little influence over the choice of carrier. I've flow TG, TK and LH in the past 6mo and I expect to be doing 4 or 5 more flights on LH/TK over the next couple of years. My trips are mostly based in Europe (I'm in the UK).

My understanding is that I need to pick a carrier to join and they will then get my miles. I was thinking that given I'm based in the UK I might be better off joining the BMI (BD) plan even though I'm unlikely to fly with them any time other than claiming the rewards as they seem to have easy requirements for jumping levels. Is this the case or would I be better of picking one of the airlines I actually fly. I don't even know if I can join the FFP for an airline I've not flown with. Also can I claim miles for flights taken before I joined the *A scheme - is that specific to any individual program?

Any thoughts would be appreciated.