When writing to the Prime Minister (UK) how do you address the letter - do you have to call him . . . ?

You f...ing wannker should do it .

He won't be opening, reading or answering the post himself, he has minions to do that, so it won't really make a lot of difference (unless you use myenzo's suggestion when you risk having your name added to a dodgy database). 'Dear Prime Minister' is probably most straight forward. However, why are you writing to him in the first place? If you live in the UK you would be better off writing to your local MP and asking him to raise the matter with the prime minister. If you ask him, he is duty bound to answer you, and also to try raising it with the PM and/or the appropriate minister. If you don't know who your local MP is, you can look it up on the link below. The PM is probably too busy to worry about your request, whereas the local MP might make more of an effort, especially if he/she needs your vote. The exception to all this would be if you were just writing for an autograph, or to ask him his favourite colour or something similar.

As a quaker I would say eschew the titles altogether and just write "Dear Prime Minister" or "Dear Gordon Brown". "Dear" is a pretty standard form of address.

As `Dubya` did to Blair .. "Yo Blair " :)

I think it should be "Dear Sheriff of Nottingham"

Hey you...Bum!. It will get straight to him.

dour scotch git get your arsenal in gear etc

Dear Prime Minister.

Whatever makes you feel comfortable...I guess you would not want to start you letter with an insult.... Dear Mr...... Mr PM Mr GB I think those three will do it for me.