In The Gatekeepers, the documentary made about Israel's internal intelligence, Shin Bet, one of the most striking interviews with six former leaders of the agency is with the charismatic Ami Ayalon, who later became a Labor member of the Knesset. Ayalon confessed that when he was small boy he thought of the state of Israel being guided by a kindly old man who lived in a room at the end of a corridor, dispensing wisdom and guidance to the country's leaders.

When he grew up, he knew, of course, there was no such person, but as he rose to the top of the Israeli navy and later Shin Bet, he realised that there was no fount of wisdom or decency to be found at the top of the Israeli state either: just politicians and officials making questionable decisions on the hoof.

In Britain, you might say that at the end of the corridor we do have a little old lady, who has seen a thing or two in her 61-year reign and has much wisdom to offer prime ministers and senior politicians. Although her impact on policy and the standards of government is minuscule, she represents something or other that appears to be reassuring.

But what you realise when you approach Ayalon's age and you have watched British politics for a long time is that life is mostly shoddy and discreditable at the top and that that characteristic is becoming more pronounced. There are decent people doing their level best, but there are also bad ones who erode the integrity and trust necessary for a democracy to work properly. One of those is Tony Blair, who took Britain to war on a lie and who is now believed by most to have misled parliament in order to help an American president who was bent on avenging 9/11 by invading the wrong country.

It is the greatest scandal of British public life in a generation, yet Blair and his allies, such as Jack Straw and Alastair Campbell, have never been properly held to account. More than a decade after we went to war, Sir John Chilcot's report is stalled because Sir Jeremy Heywood, the current cabinet secretary, who was at Blair's side as principle private secretary during the run-up to the invasion, is blocking crucial evidence to the inquiry.

It is an unbelievable state of affairs. As the former foreign secretary Lord Owen pointed out last week, you couldn't have a more dubious arrangement. A man who was integral to the government that took us to war is now sitting on evidence of 200 relevant cabinet level discussions, 25 notes written by Blair to George Bush and records of 130 phone conversations between Blair, Bush and Gordon Brown. Heywood claims that he's bound by the decision taken by his predecessor, Lord O'Donnell, to protect the confidentiality of Blair and Bush's discussions. In effect, Heywood is claiming that he has no discretion and therefore his past as senior official in Blair's Number 10 at the time has no relevance.

What is so dismal about this situation, quite apart from the naked self-interest that it represents, is that it underlines that while the British public is expected to put up with ever-increasing levels of intrusion by surveillance, in the name of transparency and security, those in power create for themselves an impregnable bunker where honour, accountability and public opinion count for nothing. They conceal their actions and shield themselves from entirely legitimate requests from an inquiry set up by the prime minister himself.

One wonders whether Chilcot was perhaps the ultimately cynical act? Could it be that Blair and the civil servants who oversaw the preparations for war always knew that the excuse of preserving the confidentiality of the prime minister's conversations with Bush would stop Sir John's committee getting at the truth of how we were taken to war on a handful of lies? Maybe they just hope to outlast Chilcot, prevaricating until the committee drop dead and everyone has forgotten the war.

Not only should Heywood be removed from anything to do with the decision of what Chilcot is allowed to see, but, as Lord Owen suggested on Newsnight, the conventions surrounding a prime minister's dealings with a US president no longer apply: this is about the possibility that Tony Blair knowingly deceived parliament and dissembled to the nation in order to do George Bush's bidding and preserve the special relationship. Allegations don't come more serious than that. We should know what he said to Bush.

After Heywood's behaviour in the Plebgate case, when he failed to investigate inconsistencies in the evidence that would have exonerated the former chief whip Andrew Mitchell, people could be forgiven for wondering about Number 10's respect for the truth and simply what is right. Mitchell was very hard done by and Heywood was the man who could have prevented much of the shame that he endured. Maybe there are questions to be asked about the values of the cabinet secretary himself.

But in all this, there is a much bigger theme, which is seen in another sputtering inquiry into the behaviour of Blair-era politicians and officials – the Gibson inquiry into allegations that British intelligence agencies were complicit in the torture of terror suspects after 9/11 and that officials in the then foreign secretary Jack Straw's office were aware. The inquiry's investigations ended nearly two years ago and the report has been sat on by Number 10 for the past 14 months. After the NGOs and torture victims boycotted Sir Peter Gibson's inquiry, because it lacked credibility, it probably won't have the damning impact it should have when it is finally published this week.

As a result, Number 10 may get away without following up with examination of cases such as those of Abdel Hakim Belhaj, who was rendered with his wife for torture to Gaddafi's Libya in an operation involving Sir Mark Allen of MI6 during Jack Straw's time at the Foreign Office.

Scrape away at the interlocking scandals of the war on terror and the war in Iraq and you find a rot that has taken hold at the top of British state.

Whether the scandal is about the path to war, the torture of terror suspects or the exponential increase in surveillance, the common denominators are consistently the reverence for the special relationship and related issues about the powers and conduct of our intelligence services. These two have distorted the standards of public life for far too long. It is imperative that Sir John Chilcot is no longer obstructed and we get his full account of Blair's war as soon as humanly possible.