I've heard bastard (and worse) said a million times before the watershed.
I suspect whenever that happens, Ofcom get some complaints about it. Swearing before the watershed isn't allowed. For the opposite extreme, look at Japan, which has no watershed, and allows blood, death, swearing, all at breakfast time. Bet the Japanese Simpsons dub never gets any scenes cut at all. Shame that can't be said for the original English version.