> Unfortunately, these days, programme breaks are filled with ersatz
> commercials promoting other BBC services and programmes, which, personally, drive me bananas.

Sky One is worst for this - every break has at least one ad telling us just how great they are; that they air big US shows before they're aired in the US; that it's a good thing that they re-run every series of a show twice (morning and evening) in a daily slot, then when they get to the end, just start from the beginning again.