One of the most enduring mysteries of the modern world is the continuing influence of the 'Neo-conservatives'.

This is the name given to the political philosophy championed by George W. Bush and his British prime minister buddy, whom he once greeted with the words 'Yo, Blair . . .'

A dictionary definition of 'Neo-conservatism' is 'the assertive promotion of democracy and U.S. national interest in international affairs including through military means'.

Of course, this was the thinking behind the West's invasion of Iraq 15 years ago — a fiasco which I believe was the most morally shameful international disaster of recent times.

Not only did it result in the deaths of hundreds of thousands (including 179 British service personnel), but it also led to years of political chaos in Iraq, to the calamity of the Syrian civil war and the rise of Islamic State.

In any sane world, those responsible would now be pariahs — disgraced and discredited men ostracised by the media and reduced to writing their pitifully self-justifying memoirs.

But we don't live in such sane times.

War-monger Blair seems to be a constant presence in BBC studios — this week alone he used the Syria crisis to justify his calamitous invasion of Iraq, arrogantly called for a second referendum on Brexit and basked in praise at an event to celebrate 20 years since the Good Friday Agreement in Northern Ireland.

With breathtaking hubris, Blair urged military intervention in Syria. And with his typically sneering attitude to democracy, he urged Theresa May to authorise the use of the British military without a Commons debate.

He is supported by another man who pig-headedly fails to learn the lessons of history: his chief propagandist, the thuggish Alastair Campbell.

It was the mendacious Campbell, as Blair's spin doctor, who spread falsehoods about Saddam Hussein's 'weapons of mass destruction' and masterminded the use of the notorious dossier on Iraq's weapons to support claims by Bush that gave a spurious justification for Britain going to war.

There is not a jot of contrition from Campbell, who, when not also being given a comfy platform by the BBC, rages about Brexit and at critics of Blair from his splenetic Twitter account.

Meanwhile, the other Neo-conservative in the unwholesome New Labour troika that duped Britain into going to war is relatively silent. It is not hard to guess why.

Peter Mandelson has close and lucrative business connections with one of Putin's cronies. His great 'friend', metals tycoon Oleg Deripaska, along with a number of the Russian's firms, has been placed on the U.S. Government's sanctions list in response to what Washington called Moscow's 'malign activities'.

It is high time Mandelson — a member of the House of Lords — explained publicly the nature of his connections with someone so close to the Kremlin.

But the toxic influence of Neo-conservatism is not just confined to Labour. As a younger politician, former chancellor George Osborne was a junior member of that clique. A leopard doesn't change his spots. Today, he is demanding military action in Syria.

An editorial in the London Evening Standard, which he edits, was as trenchant as it was misguided. It thundered: 'Britain should take part in air strikes against Assad's forces without holding a parliamentary vote.' Across the Atlantic, although no one would ever describe Donald Trump as having a clear political philosophy, his new national security adviser, John Bolton, is a notoriously hardline Neo-con.

As one of the architects of the Iraq invasion, he refuses to apologise for that war. His presence in the White House is an added threat to world peace.

The legendary French diplomat Charles Talleyrand famously remarked about the House of Bourbon that they had 'learnt nothing and forgotten nothing'. The same applies to the Neo-conservatives as they press for the West to intervene yet again in the Middle East. The first and biggest mistake in Iraq was not to have a proper post-invasion strategy. After Saddam fell, the country degenerated into chaos and the region into a furnace of terrorism.

Likewise now, Western governments seem to have little idea of the long-term purpose of any intervention in Syria.

What are the targets? What is their long-term strategy? How do we avoid an escalation into war with Russia? We are not told.

Unsung benefits of the Commonwealth  

Next week, the Queen hosts a meeting of the heads of state of all 53 Commonwealth member countries.

The Commonwealth has many critics, who sneer that it is a meaningless relic of Britain's colonial past. They are utterly wrong.

The Commonwealth brings together 2.3 billion people — almost a third of the world's population — through mutual understanding and shared values.

Unlike Nato, it does not use force to build trust and prevent conflict. Unlike the EU, it does not encroach on national sovereignty.

Instead, it shares values through a relaxed meeting of minds and a common history.

The Commonwealth was instrumental in ending military rule in Pakistan in 2007 and was behind the international boycott of apartheid South Africa.

Also, it benefits members' economies — as shown by a study published last week which reveals that Commonwealth members trade 20 per cent more, on average, with each other and generate 10 per cent more foreign investment than other countries.

There is a reason for this. All Commonwealth countries share a form of the traditional British common law. We have the same legal system and any disputes tend to be settled far more easily.

Membership of the Commonwealth is one of Britain's unsung advantages — one that should be harnessed more after

 Brexit.