This may well be a stupid question, and it may well of been asked before![:I] but why do Virgin (and other airlines i guess!) sell more seats then are available??? ive read a couple of storys where people have not been able to get on a flight due to there being to many people! just wondering like! [:p]
All airlines oversell their flights, its not just a Virgin thing. I seem to recall reading some figures for the percentage of oversell somewhere, and some carriers go up to an alarming level (like 30%)
For every flight there is always a number of pax that do not show up, i guess this an ideal way for the airlines to recoup a nice amount of revenue, by overbooking the flights they ensure that they are always full, and therefore earning maximum profit, but then, as you point out, there will be situations where there are too many passengers for the flight, and late arrivals to check-in will find that they have been bumped to the next flight or you may be offered compensation to travel on a later flight.
If you check in early, you should not have this happen to you (although with Virgin you may get offered a Select voucher and can net a nice amount of miles)
I (touch wood) have never not made it onto a flight, even ones where every single seat on the plane was occupied.