Stunned: Tory MP and former shadow home secretary David Davis (pictured) is shocked how Blair 'cynically' used Britain's diplomatic clout to push the Iraq war

This is one of the most astonishing documents I have ever read.

It proves in explicit terms what many of us have believed all along: Tony Blair effectively agreed to act as a front man for American foreign policy in advance of any decision by the House of Commons or the British Cabinet.

He was happy to launder George Bush’s policy on Iraq and sub-contract British foreign policy to another country without having the remotest ability to have any real influence over it.

And in return for what? For George Bush pretending Blair was a player on the world stage to impress voters in the UK when the Americans didn’t even believe it themselves.

Blair was content to cynically use Britain’s international reputation for honest dealing in diplomacy, built up over many years, as a shield against worldwide opprobrium for Bush’s ill-considered policy.

Judging from this memorandum, Blair signed up for the Iraq War even before the Americans themselves did. It beggars belief.

Blair was telling MPs and voters back home that he was still pursuing a diplomatic solution while Colin Powell was telling President Bush: ‘Don’t worry, George, Tony is signed up for the war come what may – he’ll handle the PR for you, just make him look big in return.’

It should never be forgotten that a minimum of 120,000 people died as a direct result of the Iraq War.

'Just make him look big': Bush's end of the deal seemed to be inflating Tony Blair's position on the world stage

What is truly shocking is the casualness of it all, such as the reference in the memo to ‘the day after’ – meaning the day after Saddam would be toppled.

The offhand tone gives the game away: it is patently obvious nobody thought about ‘the day after’ when Bush and Blair met in Crawford.

And they gave it no more thought right through to the moment ‘the day after’ came about a year later when Saddam’s statue fell to the ground.

We saw the catastrophic so-called ‘de-Baathification’ of Iraq, with the country’s entire civil and military structure dismantled, leading to years of bloodshed and chaos. It has infected surrounding countries to this day and created the vacuum into which Islamic State has stepped.