There are several Britcoms well known to US audiences. Not a single one of them has their own board though, while Canadian sitcoms such as Corner Gas and Check It Out do. The Britcom forum could be divided up more while still leaving a general board there.

The Britcoms section has only 3,833 posts. It has never been very active. I don't see the need for separate boards. I guess they aren't many people's cup of tea on here.