why is it not permitted to use certain words that in england mean a type of food or a servant in a public sch?

Faggots are a traditional meat ball of pigs liver

We are "two countries separated by a common language". Slang varies even more than Standard English. Most slang terms would simply be unintelligible on the opposite side of the Pond but some have very different meanings. In the US, vests and knickers are worn on the outside. In England, they are underthings. To the British, a rubber is used to rub out pencil marks. In the US, it is used "to prevent disease". Nice euphemism. In addition, styles in language change over time even in the same country. A WWI era song has a verse, "While you've a lucifer to light your *** . . ." (A match to light your cigarette). More recently, I remember that "gay" meant "happy". Pity the poor censors at Y!A. They have to make decisions that will avoid offending people while still allowing clear communication. They sometimes foul up. While I can see where they might want us to use "lady-dog" in preference to the word that is unoffensive when used literally, for awhile they also censored "batch", which made writing about brewing beer a bit more difficult. You can't win.

In America you can bum a cigarette and in England you can borrow a *** but you wouldn't do both, especially in public.

The word *** can also be derogatory in England. I know fagging in public schools can still go on in some ex colonies like South Africa. It is quite an unpleasant experience I read, perhaps even somewhat brutal. Just for the record it means the younger pupils have to do things for the older pupils. In England this meant things such as warming up a toilet seat. You can see how it could easily become derogatory seeing as the act of being a *** is rather derogatory; a rather unwilling servant/slave.

Here's a reverse situation...in the UK, at least some years back, it was a way of asking a guest what time they wanted to be waked up in the morning..."What time shall we knock you up?". In the US, high hilarity at this phrase, since being "knocked up" is another, and cruder, way of saying someone is preggers. You can imagine how the Yank military types had fun with that one. In retaliation, the short Army jackets worn by some units were called "bum freezers" - and the Yanks wondered what poor hobo was being frozen out in the cold. Ba-da-bing.

No idea.

My husband loves f a g g o t s of the Brain's variety in a rich West country sauce. They are made from liver, lungs, onions and meat.

A f a g in England, apart from being a slave at public school is also what people commonly refer to as a cigarette.