Labour politician Jack Straw recently announced he will not stand for re-election as MP for Blackburn, his parliamentary base since 1979.

Straw was home secretary, foreign secretary and leader of the Commons under Tony Blair, then justice secretary under Gordon Brown.

Saturday's Guardian carried an interview with him by journalist Decca Aitkenhead.

There were a few points of interest in the interview - Straw's annoyance when she arrived, as if a police officer had come to search his house, is one. His treatment of his assistant is another ("I don't think I've ever seen an assistant treated so imperiously"). And apparently he prefers to read out things he has said in the past to saying what he thinks.

Is this a man beset by his conscience? Or just ill at ease with journalists?

Still, Morning Star readers would have conducted a rather different interview.

Serious questions relating to his time in office - most notably when as foreign secretary he backed the invasion of Iraq - were not raised.

So it's no surprise that Straw expressed no self-criticism over Iraq, none about indefinite custody for non-British nationals suspected of terrorism, none about Britain's complicity in extraordinary rendition.

None about having sometimes said, to borrow a phrase from Gulliver's Travels, "the thing that was not."

Straw's 2012 memoir Last Man Standing is not without revealing moments of frankness - and of reality denial.

He explains why he chose a parliamentary career. "I decided that being an MP sounded a great deal easier as a way of serving the Labour Party than delivering its leaflets in the rain."

In his youth Straw took part in CND-organised Aldermaston marches and worked on the Labour left alongside communists. Before long he became president of the National Union of Students.

By that time he had accepted an invitation to meet then prime minister Harold Wilson. In 1975 he played a part in the campaign against joining the European Common Market.

After becoming an MP for Blackburn in 1979 he voted, in 1981, for Tony Benn as deputy leader.

But now he says: "I should not have done so." It's about that time that he seems to have said a cheerful goodbye to any left-wing political position.

Straw volunteers his delight in mixing with other members of ruling elites. When foreign secretary he became friends with US secretaries of state Colin Powell and Condoleezza Rice and with Saudi Arabia's long-serving foreign minister Prince Saud al-Faisal.

He describes the prince as "wise, shrewd and compassionate." Maybe he never dipped into Said Aburish's authoritative 1997 book A Brutal Friendship, which shows up the Saudi government as a "xenophobic clique who run a country they think they own, a feudal family with criminal implications."

We might be forgiven for concluding, based on Straw's blessing for Blair's criminal role in the invasion of Iraq, that his primary objective was simply to keep his Cabinet seat.

On October 22 2002 the diary of fellow Labour MP Chris Mullin records Straw as distancing himself from nutcase US Republicans but also saying: "I know for a fact that [George W] Bush doesn't want a war."

He was saying the thing that was not.

Over many months before the US-led invasion began on March 20 2003 Straw helped his master develop an advance alibi for the war.

Such aggression would not be a crime, since Saddam Hussein's government would be the aggressor, or at least the potential aggressor.

Evidence for this was derisory, so the evidence "proving" the threat of the now infamous "weapons of mass destruction" canard had to be fixed around the policy.

At a later stage, in March 2005, Straw was to claim that the attorney-general's legal advice had not undergone serious change in a week.

Actually Peter Goldsmith's advice on March 7 2003 was that the war would "arguably" be legal. On March 14 he said it would "definitely" be legal.

The truth emerged not long after Straw's protestations. Sadly the Guardian interview did not bother to ask whether being caught out in these ministerial fibs ever troubled him.

If Straw had retained the convictions of his youth he would have marched with two million others against the Iraq war. Instead he loyally supported a belligerent US imperial regime and its British stooge.

Andrew Rawnsley's 2010 book The End of the Party, composed with access to new Labour's inner circle, tells us that in the final weeks before the invasion Straw asked Blair to consider alternative ways of supporting the US to sending troops. Bush and his defence secretary Donald Rumsfeld offered Blair the same option.

But Straw's memoir states that he supported the war. And it insists that "the inconvenient truth, however, is that Iraq is a better place."

Reality continues to bellow otherwise.

Jump to Straw's role in undermining the right to trial on specified charges and in extraordinary rendition.

Of the original Guantanamo detainees, rendered there from Afghanistan following the US-led invasion of 2001, nine were British.

Straw scored high marks when he qualified as a barrister. He knew perfectly well that a cherished principle of civilised legal systems is that no-one taken into custody should remain there without access to legal representation or to trial by a court on a definite charge.

He knew too that the Bush government had decided it could arrest, detain and torture outside these core legal parameters.

Nevertheless neither he nor fellow barrister Blair took a public stance to contradict the US position for more than two years, other than - in the words of international lawyer Philippe Sands in his book Lawless World - "mouthing generalities about certain unspecified 'reservations'."

Only in March 2004 were five of the British detainees at Guantanamo released without charge and returned to Britain - without apology.

The other four were returned the following year, though several legal UK residents who are not British nationals were held longer, and Shaker Aamer remains in the concentration camp to this day.

Meanwhile questions were being asked about direct British complicity in US-sponsored rendition.

It emerged that two Pakistani nationals had been transferred from Iraq to Afghanistan with MI6 involvement and that the same agency was reportedly complicit in the dispatch of two Libyan dissidents to the Gadaffi regime's torturers around the time that Blair struck his deal with the Libyan leader in 2004.

And Britain had established its own version of Guantanamo in Belmarsh prison, where non-British terror suspects were held without charge or trial from December 2001.

In December 2004 Britain's final appeal court found - to the public wrath of Straw and David Blunkett - that the government had been acting illegally.

Lord Hoffman said: "The real threat to the life of this nation, in the sense of a people living in accordance with its traditional laws and political values, comes not from terrorism but from laws such as these."

The government's response was to introduce control orders.

Then came Straw's notorious answer in December 2005 to probing questions about British collaboration in extraordinary rendition when he appeared before a Commons committee.

"Unless we all start to believe in conspiracy theories and that the officials are lying, that I am lying, that behind this is some kind of secret state which is in league with dark forces in the United States ... there is simply no truth in the claims that the United Kingdom has been involved in rendition."

Once again Straw spoke with a forked tongue.

Three years later his statement was corrected by his Foreign Office successor David Miliband.

Britain's complicity was admitted. But even now the number of rendition cases in which Britain was involved is unknown and information concerning them continues to be hidden from public view.

Pressure for more light to be shone on this dark place and for the long-blocked release of Shaker Aamer from Guantanamo is vital.

The Guardian might go soft on him, but Straw should not imagine that retiring from the House of Commons will end public interrogation about the unsavoury aspects of his career.

The cautionary tale it represents may usefully be reflected on by whoever follows him as Blackburn's member of Parliament.