MPs were transported back to March 18, 2003 last night when they voted - after a major Labour revolt - to spend £20bn on renewing our Trident nuclear weapons.

On that dramatic night, Tony Blair only won approval to join the Iraq invasion with the help of Tory votes, after 139 Labour backbenchers rebelled.

Controversy raged over the Attorney General's last-gasp declaration - in defiance of almost all other expert opinion - that the war was legal.

Soon after, of course, we learned the Prime Minister had promised George Bush that British troops would join the fighting a full year before securing Parliament's backing.

Four years on, the parallels were striking as Mr Blair again stood at the despatch box to warn that the nation's security was in peril if MPs ducked a difficult decision.

The Prime Minister was at his most offensive as he labelled his opponents' position "absurd" and ridiculed them for "sitting on the fence".

The first parallel was that, with scores of Labour MPs defying a three-line whip to vote against Trident, the Government again got home only with Conservative support.

Second, the rebels had demanded the release of the attorney's advice on the legality of the Trident update, as lawyers argued it breached the Nuclear Non-Proliferation Treaty.

Third, Mr Blair was again accused of pre-empting Parliament's decision in a December letter to the US President, which explained how Britain was taking "the steps necessary" to renew Trident.

But fourth, and most significantly, the rebels' main argument was that a crucial decision was again being rushed for political, rather than military, reasons.

Back in March 2003, the war was launched even as UN inspectors in Iraq became increasingly convinced that Saddam's weapons of mass destruction were a mirage.

Of course, that rushed decision went well - hundreds of thousands of Iraqi dead, the country a terrorist haven and the world a more dangerous place.

The Government insisted that yesterday had to be Trident D-day because our four submarines will be defunct from 2024 and it takes 17 years to develop a replacement.

However, this sits uneasily with the success of the Americans in extending the lifespan of their Trident subs by 44 years. The missiles themselves will last until 2042.

So if, as the rebels claimed "the case is not yet proven", what political event could possibly be driving the decision?

Well, it's a shot in the dark, but Mr Blair will leave No 10 within a few months.

Last week, York MP Hugh Bayley said local doctors suspected the Clifton treatment centre - run by private health firm Capio - is being paid for more operations than it is carrying out.

During a Commons debate, he complained that his attempts to find out the truth using Parliamentary questions had run into a Department of Health brick wall.

The Labour backbencher was told that "payments for services and operational costs of Capio UK is commercially sensitive" - even though it receives taxpayers' cash.

In reply, Health Minister Ivan Lewis sympathised and suggested a solution - that Mr Bayley should ask Capio itself whether the taxpayer was being ripped off.

What a brilliant plan! After all, why would Capio possibly refuse? And why is it that politicans entering government also enter cloud cuckoo land?