It's not only the accent but the words they use. If you know British vocabulary therès lots of words British people would never say.

Ask him what Bubble & Squeak is. Unless he's a real Anglo-phile, has lived in England, or has worked with working & middle-class Brits for a while, he probably won't have a clue. Also, if at a restaurant, bar, or coffee shop, he asks for the check, he's a fake. Brits ask for "the bill". Also, if he tips well (except in the US), he's not a Brit. Also, if talking about school: the dead give-away is if he says "Math" instead of "MathS" or "SportS" instead of "Sport". (The Brits, Irish, Aussies, Kiwis and South Africans "study Maths" and "play Sport"). Brits also say "revise" or "do revision" where an American would say "review". 1 thought though: if it's a working-class regional accent, those are very hard to do right if you're not a native, and most non-Brits get them horribly muddled when imitating them. The problem is it's very hard for a non-Brit to recognize it. But if they speak with an upper-class university accent, it could very well be completely "faked" and the person still be a genuine Brit (and a genuine university grad) who just learned to drop his natural accent to fit in with the elite at school. A few other things a Brit would say or know: "Public School" = a private school, primary and/or secondary level "Crisps" = potato chips "Chips" = french fries "Mash" = mashed potatoes "Solicitor" is an attorney/legal advisor -- but not a Barrister (which is a trial-lawyer/advocate). Also Solictors aren't members of "the Bar", and they don't have DA's or ADA's: they're called QCs (Queen's Councils) a "Trunk Call" = a long distance call "Trainers" = sneakers "Jumper" = wind-breaker "Queue" = waiting line, and "queue-up" = line-up "Tan Trousers" are Khaki Pants and "Khaki Pants" are soiled underpants. A Guinea (in modern usage) is 1 pound 5 (new)pence, and is used mostly in gambling A Half-Crown was a coin worth 1/8 of a Pound (or 2s 6p) and the last one was issued in 1970 (the year they went to a decimal currency) Anti-Clockwise means counter-clockwise Big Ben is the name of the bell, not the clock or the tower Brits say "RSC", not "Royal Shakespearian" and "Church of England" (without a 'the' in front) not "Anglican". The town of Slough (outside London, near Windsor) rhymes with 'cow'. Prince Charles is also ArchDuke of Cornwall as well as Prince of Wales There were only 12 episodes of Fawlty Towers The Boot is the car trunk and the Bonnet the hood Lloyd's of London isn't an insurance company, it's an underwriters' exchange Richard Branson wanted to call his Coach Class "RiffRaff", but the Ministry of Transportation wouldn't let him. He also made his first fortune legally smuggling English record albums out of and then back INTO England, circumventing the UK's confiscatory VAT tax. The Channel Islands - while English - are niether part of England nor the United Kingdom, but are independent states held of the Crown. Gordon Brown is Labor, not Tory, and he was Blair's Chancelor of the Exchequer Disraeli was Tory, not Liberal. Churchill was PM twice (1940-45 & 1951-55) Oxford specialized in the Humanities and Arts -- you go to Cambridge for the Sciences and Engineering If he's a Brit, then he's a British SUBJECT, NOT a British Citizen. The University of Liverpool is Britain's University of Phoenix - i.e., their on-line diploma mill. Millwall (the soccer team ... I mean "Football Club") is pronounced MELLWELL and referred to by fans as THE DEN, and is based in the London area of the same name on the western side of the Isle of Dogs, in the London Borough of Tower Hamlets, south of the developments at West India Docks, including Canary Wharf. FYI: Bubble and squeak (sometimes just called bubble) is a traditional English dish made with the shallow-fried leftover vegetables from a roast dinner. The chief ingredients are potato and cabbage, but carrots, peas, brussels sprouts, and other vegetables can be added. It is traditionally served with cold meat from the Sunday roast, and pickles. Traditionally the meat was added to the bubble and squeak itself, although nowadays the vegetarian version is more common. The cold chopped vegetables (and cold chopped meat if used) are fried in a pan together with mashed potato until the mixture is well-cooked and brown on the sides. No one knows for sure how the dish got its name.

Pat him, on the shoulder, smile and say 'you're such a wanker'. If he punches you in the face, he's british.

you probably cant tell

If his name is not "Terry," that's a dead giveaway. Watch how they finger count: Brits/Europeans start counting with the left thumb, Americans with the right index finger..