IIRC, Nixon got a similar reaction in Great Britain when he made the V-for-Victory sign but had his hand backwards.
Yes, the V-sign with your knuckles facing away from you is roughly the equivalent of the middle finger in the U.K. Apparently, there was a Welsh soccer player who used to do it regularly, but I don't think he was fined.
Was Churchill trying to convey two different messages? Hmmm.