Where on earth would the Fulcrums have come from, Denmark? And with their range issues, where would they have been going, Norway?
Since you ask, why not? Places are sometimes invaded during wars.
But in all seriousness, none of this puts the lie to what I originally proposed - that the RAF simply didn't have a useful fighter force for decades (and only does now depending how you feel about Typhoon.) The fact that this might have been done quite deliberately on the assumption that it probably wouldn't be needed isn't entirely comforting.