Looking for the last item in a string set in a particular character style

Question

I should find each space that is the last character in a string set in a particular character style. For example, in the passage "123 456 789" (the underlined part here indicating a passage set in a particular character style), my ideal GREP search would yield a match after the digit 6.
How do this?

Answer 1

Excellent! This works perfectly. I have used your string with the bold character formatting, and replaced the matches with [nothing], set in None style.
On second thought, I was surprised that it indeed had worked: why was the space replaced, and not deleted? Shouldn't I have used
(?<!.)(\s)(?=\w)
and replaced it with
$2