War in Iraq memo
From a secret Downing Street memo written in July, 2002 (eight months before the war began):
The Foreign Secretary [Jack Straw] said he would discuss this with Colin Powell this week. It seemed clear that Bush had made up his mind to take military action, even if the timing was not yet decided. But the case was thin. Saddam was not threatening his neighbours, and his WMD capability was less than that of Libya, North Korea or Iran.
Although the UK press is mostly interested in how this will play in the current UK general election, it appears that high-level doubts about WMD were voiced very early.