Some people want to pretend to be from the UK, so that their English ability is never questioned and can be used to dominate others. In this article I will explain the basic steps on how to pretend to be a British English speaker. First it is important to never meet anyone who has ever been to the UK. Certainly avoid meeting anyone who has ever lived there. They will instantly be able to tell that you are faking.
Wear conservative upper class clothes to look like you are someone important. Always wear a tie except when swimming or showering. Ordinary people in England wears suits and ties only as often as people do in China, but you are trying to look special. Always wear a gentleman's hat outdoors (no baseball caps). Use a hat such as a fedora (often called a trilby in England).
Pick a town or village some place in England; also pick a boarding school. Read about them online. Remember to call it a public school. Talk to people about related historical events. Be careful to choose a real place. As a joke, a fake Gloucestershire village was once created in online records by an Oxford professor (whose name will not be mentioned). Be able to describe your family's 50 room country house, with its ten acre lawns, Rolls-Royce cars and the many servants. Never mind that this is a fantasy world. Maybe read a lot of PG Wodehouse as background material. (He wrote many stories about upper class life in England.)
Use some British English words. Only use the British Imperial system, never the metric system. Potato chips are crisps, French fries are chips, sausages are bangers. An umbrella is a brolly. A ball-point pen is a biro. (However you might want to use a fountain pen anyway to appear more upper class.) Cookies are biscuits, biscuits are buns. A trash can is a dustbin. A big road is a motorway.
There are also slang words that you can use to sound exotic and British. Rain is Andy Cain. (I am wet because I was caught in the Andy Cain.) Soap is a band of hope. To wash is Bob Squash. To be married is cash and carried. Make others up as you need them. The final word in your slang expression should rhyme with the original word. Other people may not understand you, but that is for the best.
Use unnecessarily long words to sound well educated, even if you are only exhibiting pretentiousness. Use sesquipedalian loquaciousness to describe your speaking style. Use the word amongst instead of among. You do not read comic books, you read sequential graphic novels. Say reverse the polarity of the neutron flow when talking about any malfunctioning electronics. You will be thought of as patronizing, polysyllabic, ponderous, pretentious and pompous.
You don't need to actually speak with a real accent, just sound different and more difficult to understand. Speak with a deeper voice. Drop the letter h at the beginning of words. Pronounce all short a sounds (as in cat) with a broad a (as in father). Drop the letter r at the end of words. Use a neutral -uh- (schwa) sound for any -er/-re ending. Pronounce all place names ending -ham, as 'm (Birming'm, Notting'm etc.) Practise talking like this every day. Many people will not understand what you are saying, but they will assume that the fault is theirs.
All of the more intelligent readers will have noticed that this article is a joke. However it is a joke with a moral. The desire to pretend to use British English to sound superior is useless. (Pronouncing cat or jam with a broad a will just sound idiotic! Rhyming slang is not upper class in the UK.) It is much better to try to speak clearly and simply and not try to fake anything. The UK has many local accents, there is no one official British accent. In the UK most people are ordinary, wear ordinary clothes and don't have huge country homes, servants or Rolls-Royce cars. (Really, I used to live there.) Also they use the metric system. The purpose of language is to communicate, not pretend to be something that one is not.