This is what drives me nuts about Americans, they think there is a British accent... there is NO British accent. There, is jordie, scouse, manc, west country, brizzle, cockney, norfolk, brummie, various welsh accents from cardiff to the valleys, numerous scottish accents (provided they stay in Britain come september) and hundreds in between.
What Americans think is a British accent is the older style upper crust Etonian Queens English that very few people actually speak with.
Like wise I don't assume there is one American accent, hell there are a number of accents in New York alone!
So get it through your thick skulls MS don't assume every one will accept what you consider a British accent. I used the UK Siri and changed to the US Siri when I had an iPhone because the "British" version sounded like a pretentious *****.