Absolutely, Alan. I too have tired of hearing people prefacing their reply to a question posed to them with the word "So". It rankles me as much as it apparently does you. I especially hear this said all the time while listening to NPR (National Public Radio) here in The States, and which might be compared to your BBC over there on those grouping of islands off the European continent, AND where you guys STILL for some inexplicable reason spell certain words within our shared language with that oh so needless superfluous letter 'u'!

(...however, you DO know why this "So" thing has caught on, don't you?...It's because whatever words come after it will sound non-committal, and thus in hopes of lessening any possible negative blowback directed to the person who's made the comment, because it then sounds much less like they've attempted to make a definitive statement)