The famous "V" sign is considered obscene in the UK, Emma, if the knuckles of the fingers forming the V are facing outward. It is exactly the same significance as "giving the finger" in North America. (perhaps Brits feel that 2 fingers are better than one...)

If the knuckles of the fingers forming the V are facing inward, however, which means that the other 2 fingers and the thumb are out in front, then it is not considered obscene. Churchill's use of the "V for victory" gesture was of the latter type, not the former.

It's a bit easier and more comfortable for the hand to flash the common insulting V sign than it is to do the V for victory sign.