Who is Sir Alex Allan? Prime Minister's adviser quits amid Priti Patel fallout

In 2012, Sir Alexander Claud Stuart Allan made a promise. As the Prime Minister's adviser on ministerial standards, he told a public administration committee of MPs that he would step down if he ever felt he was being "bypassed".

On Friday, it would seem, he made good on his word.

Sir Alex's resignation comes after his report into allegations of bullying by Priti Patel, the Home Secretary was seemingly ignored.

On Thursday night, it was revealed that Boris Johnson judged Ms Patel had not breached the ministerial code – despite Sir Alex concluding that she had "not consistently met the high standards expected of her".

In a statement, Sir Alex said he felt it "is right that I should now resign from my position as the Prime Minister's independent adviser on the code".

Sir Alex made his earlier comments on resignation eight years ago when he was accused of being a "poodle" in a "non-job". MPs called on him to resign after it emerged that he had not been asked to investigate whether Jeremy Hunt broke the ministerial code.

At the time, MPs demanded an investigation into why Mr Hunt, then the Culture Secretary, was alleged to have allowed an adviser to give confidential information to News Corporation during its bid for BSkyB.

Mr Hunt maintained that he "strictly followed due process" in the way he handled the bid and said it was not true that the firm had any "back channel" of influence when he was ruling on it. His special adviser, Adam Smith, quit over contact with the firm that he said "went too far".

However, after David Cameron said he had "no plans" to refer the case to his independent adviser, MPs were left asking "what is the point" of Sir Alex.

Privately educated Sir Alex, who studied mathematics at Cambridge University, has had an esteemed career that saw him work as principal private secretary to both John Major and Tony Blair. He was later employed as British high commissioner in Australia and, upon returning to the UK, became permanent secretary at the Ministry of Justice.

Subsequent employment included being chairman of the joint intelligence committee. While holding the title of independent adviser – a job created by Gordon Brown, and in which he was employed under David Cameron – he was also chairman of the QC appointments panel and a board member of the Parliamentary and Health Service Ombudsman.

Outside work, Sir Alex is a keen sportsman and once windsurfed down the Thames during a train strike, supposedly dressed in a suit and a bowler hat. A bridge enthusiast, he is also said to be interested in computers and rock band Grateful Dead.

Despite his background in the intelligence services, he was once reprimanded for having published his personal details on his own website, including his address, telephone number and details of family and friends.

In 2008, it was was his role in the intelligence services that saw him become the potential target of an attack by adversaries, although Government sources insisted there was no sign of foul play. Responding to news that he had been found collapsed at home, David Miliband told the Commons that he had "known Alex Allan for 11 years now and a couple of hon. Members referred to his recent illness and passed on their best wishes to him".

He said: "I am delighted to say that he will be able to recognise the warmth and strength of that feeling when it is passed on to him in hospital. I am sure that we all wish him a speedy and full recovery from his illness."