Where do I send a letter I wrote to the British Prime Minster??

Question

I have looked everywhere and I can't find it, where do I find an address to send a letter to the british Prime Minster,

Answer 1

10 Downing Street,
London,
SW1A 2AA

Answer 2

Every British Prime Minister has lived and worked at the same address since sometime in the 1730's.

The address to write before Mr. Blair steps down is:

P.M. Tony Blair
10 Downing Street
London SW1A 2AA
England

There is also a website available with a lot of history on past and present Prime Ministers, but they say if you desire a reply it is best to write. Just put "10 downing street" into your search engine and you'll find it.