I've just had to sit through what was effectively a Party Political Broadcast by Labour for Tower Hamlets under the guise of something called "The Political Slot" on Channel 4. It had two "local" people, (the female of which who, when compared to the Tower Hamlets Labour Party website looked a little bit like one of Labour's Councillors) talking about how Tower Hamlets was the most wonderful place in the world to live (highly suspect) and it was all because of the "Labour Government". Then the female said "that's why I'll be voting Labour" whilst Labour adverts scrolled across the screen. There was no indication that the piece was a PPB, but one has to presume that the production costs will be on Tower Hamlets Labour electoral expenses. I've emailed them to find out (and CC'd the Electoral Commission for good measure).
Update: The Councillor I mentioned above has kindly informed me it wasn't her. She says she has a welsh accent, so unless she was doing a very good barrow girl impression it was merely a lookalike. Oh yes, she threatened to sue me as well. Interestingly she didn't mention the issue that the film might have breached electoral law, or whether it's going to be included in their electoral expenses.