In 2017, Mr Portillo made a speech at a Futurebuild event in which he was asked what his advice would be to David Cameron following his exit from Number 10. Mr Portillo slammed his fellow Conservative, accusing him of being one of many prime ministers to treat the House of Commons as a "public convenience". He said: "He should have stayed in the House of Commons. I don't like prime ministers who use the House of Commons like a public convenience. "They pop in for a while, they become prime minister then as soon as they've used the place they leave it. Tony Blair was the same." Mr Cameron released his memoirs last week, in which he explained the thinking behind his decisions as Prime Minister.
He admitted that he underestimated the rows that would engulf the country as a result of the EU referendum in 2016, and that it was called, in his view, at the wrong time.
However he did not say it was the wrong decision despite its devastating effect on his career.
His premiership is remembered by most as a humiliation at its conclusion, but Michael Portillo had damning words for the former Prime Minister regarding his entire six years at the helm.
Mr Portillo went on lauding Winston Churchill as the ideal Prime Minister, due to his long career in the Commons after leaving Downing Street.
Portillo slammed Cameron for leaving politics after the referendum (Image: getty)
Portillo accused Cameron of using Commons as a 'public convenience (Image: getty)