For almost every prime minister, the number one item on their agenda when they leave office is the small matter of earning as much money as possible, as quickly as possible.

Doing so without the help of unsavoury characters is not difficult: a seven-figure deal for your memoirs, the same again for public speaking and a comfy chair on the board of one of the big City firms should cover it.

Theresa May, Sir John Major and Gordon Brown have all managed quietly to get on with the business of cashing in without attracting huge controversy. All three, for example, are signed up to the same public speaking agency in Washington DC, where fees for a single speech can run to six figures. Not bad for less than a day’s work.

Why, then, has David Cameron proved so incapable of avoiding trouble since he left politics in 2016?

Already the subject of a Cabinet Office investigation into his alleged lobbying on behalf of the collapsed financial firm Greensill Capital, today Cameron resigned as chairman of the advisory board to Bermuda-based software firm Afiniti after its founder was accused of sexually and physically assaulting an employee.

The question Cameron must surely be asking himself is whether he could have seen any of this coming, or whether he is just unlucky.

According to those who know him – and his controversial former bosses – the answer is, at least partly, the former.

Chris Bryant, chairman of the parliamentary select committees on standards and privileges and a long-standing scrutineer of Cameron’s outside interests, suggested the former prime minister “lacked a moral compass”, and even if that might seem overly harsh, few people could disagree that he has proved a poor judge of character in the past.

Bryant suggested Cameron had a habit of becoming “beholden” to people to whom he would be better advised to give a wide berth, like Rebekah Brooks, the chief executive of Rupert Murdoch’s UK newspaper empire.

Cameron came under fire during his premiership for his close friendship with Brooks, a fellow member of the so-called Chipping Norton set in Oxfordshire, after it emerged he had met her 22 times in six years– an average of once every three months – as well as texting her regularly. One text, telling her to “keep your head up” as the phone hacking scandal erupted, now seems spectacularly ill-advised, and points to Cameron’s tendency towards misplaced loyalty.

In another text, he thanked her for letting him ride one of her family’s horses, saying it was “fast, unpredictable and hard to control, but fun”. It could equally be a description of his employment strategy since leaving Downing Street.

His portfolio of jobs might best be described as high-risk, high-reward: on his official website, Cameron says he is working with businesses that are “all concentrating on innovative technology-driven sectors, including Fin-Tech, Medi-Tech and AI [Artificial Intelligence]”.