Wikipedia's take...

to the best of my knowledge wikipedia is a non-partisan site which makes this all the more interesting;
The "Downing Street memo", sometimes described by critics of the 2003 Iraq War as the "smoking gun memo", is a document obtained from an undisclosed source containing minutes taken during a meeting, on July 23, 2002, among United Kingdom government, defence and intelligence figures, discussing the build-up to the war. The memo was printed in The Sunday Times on May 1, 2005, and is available in full on Wikisource (http://wikisource.org/wiki/Downing_Street_Memo). Its authenticity has neither been confirmed nor denied by the British government. There have been repeated requests for clarification, from the media and from a contingent of United States Congressmen, led by Representative John Conyers of Michigan.

46,000 UK troops were sent to join the US-led action, the largest non-US contingent of the Iraq invasion. The memo gets its name from London's Downing Street, where the official residence of Prime Minister Tony Blair is located (at 10 Downing Street). It is a metonym for the UK government in the same way that "Washington" is a metonym for the United States government.

On June 18th, 2005, the Associated Press reported that Michael Smith, the reporter who first obtained the memos, said that he protected the identity of the source he had obtained the documents from by photocopying them, returning the original documents to the source, retyping the documents from the photocopies, and finally destroying the photocopies. Retyping documents on a typewriter, rather than a computer, is a common security practice among reporters, but the complexity of the process has led some to question the documents' authenticity. [1]

notice how they have smoking gun in quotation marks. Man I am not seeing the flames yet but the temperature is rising people.