Not as many as those who were prepared to fight, by a long shot.
By 1939 Mosley's a joke, although there are a minority of pro-Germans in high levels - like the Duke of Wellington (forgotten which - might be the 5th?), they don't have much influence. The British people were prepared to negotiate with Hitler up until he took Czechoslovakia. Before then, the majority had believed all Hitler wanted to do was reverse the treaty of Versailles and take back what was rightfully German.
Agreed, there were Nazi sympathizers in the US and France as well but not very many of them. A country with a population the size of any of the Great Powers is going to have its share of wierdos.