Ok, so that's the history book version, which, like most history books, is falsified.
One, the American Colonies were private companies in which the King of England, not the British Crown, was a majority shareholder. The King -a German who was heartily despised by most people -expected the British Government to administer and defend his assets for him. Parliament asked him to charter the Colonies as Boroughs so that they could elect MPs and raise their own taxes. He refused, wanting to keep his money. Parliament was thus forced to impose a few luxury taxes on the Colonies. Taxes which did not effect ordinary people, but which incensed wealthy businessmen such as Washington and Jefferson. So there was a coup -a seizure of power by a political faction - not a revolution, which is a popular uprising. Washington and company were running a guerilla campaign with little success. The King demanded more British troops, Parliament refused -they didn't care - so the King hired German mercenaries - the Hessians. The French then sent in several crack regiments from Canada in the hope of drawing British troops out of India, where the French had ambitions. Their plan didn't work and the British Government let the Colonies go in the certain knowledge that the profitable trade between Britain and America would restart soon enough, even if the King lost his personal piggy-bank. British interests were in the East, not the West, and America had been costing us far more than we gained from it.
Two. Nobody would ever have shipped slaves to America if your lot hadn't been so mad keen on having them, so don't blame us for that! There was nothing stopping Washington and the rest abolishing slavery after independence, but somehow among all the talk of 'Liberty' that sort of didn't happen.
Three. The idea that the US somehow 'saved' Britain in the Great War and again in the Second World War is one of your more pernicious delusions. Germany didn't even come close to invading the UK during the great War, and the tardy arrival of US forces made no difference to the outcome. In the Second World War, the German threat to Britain was decisively ended in the Battle of Britain in 1940 -without air superiority, the Nazis could not hope to launch a successful invasion. The intensive bombing campaign known as the Blitz ended in 1941, when it became clear there would be no surrender. Even the U-boat blockade was only partially successful. Americas' intervention was due to your fear of Russia turning all of Europe Communist, and with the connivance of that maniac Churchill, served only to prolong the war for a further three years. It would have been perfectly possible for Britain to negotiate a peace with Germany after 1941, but Churchill - a pro-American fanatic -refused.
Four. Far more people come here than leave, sadly. Anyone daft enough to go to America is nobody we need, but we do need the space they leave behind them.
Five. Brexit is not about economics but about sovereignty. It's also about the fact that nothing in Europe has changed since the 19th Century: the French and the Germans are still at each others' throats, and we in Britain are sick of refereeing between them!
Six. The Crown, as an institution, is central to our system of government. It is the reason why Boris Johnson doesn't have a tenth of the power Trump has, so can't do a tenth of the damage Trump did. The bunch of freeloading Germans is the price we pay for that.
Seven. Most British people have clean, healthy teeth. What we do not do is spend thousands of pounds on unnecessary cosmetic orthodontics. Just because we don't all have artificially bright, straight, white teeth doesn't mean they aren't healthy! The same as most British men are secure enough about the dimensions of their genitalia not to need guns to 'prove' their masculinity, whereas there has to be a doubt about 'men' who need plate armour to play rugby!