That is a gross over-generalization. There is no such thing as a "British accent", and I am saying it with some authority as a Bloody Foreigner™ living in the country. There are as many accents in Britain as there are Brits. It took me years to even start to understand an ex-colleague of mine who was from some deep recesses of Scotland and who consistently said "fail" for "file" and "tame" for "time". I have similar problems understanding one of my current colleagues. I am forced to answer pretty much 90% of his utterances with a simple, "eh?"

Yet, for some reason, when they interview someone on the British TV who is foreign but speaks beautiful, clear to understand English, albeit with an accent, they put subtitles on the screen. But when they interview someone like my colleague whom I have no chance of understanding, they don't.