Comparing himself to a booster rocket that had fulfilled its mission, Boris Johnson said farewell to his Downing Street residence and office on Tuesday and described his future plans as a return to a quieter life.

In what was a typically bombastic speech, Britain's outgoing prime minister pointedly took aim at those lawmakers in his Conservative Party he blames for forcing his resignation and, almost to prove them wrong, went on to list what he sees as his successes during his time as premier.

He also offered a tantalising reference for classics scholars, when he compared himself to Cincinnatus, a Roman dictator who, despite his old age, left his small farm to take control of the Roman state to fight an invasion in 16 days.

Cincinnatus returned to his farm, but legend has it he was recalled a second time to fend off another crisis, prompting some to wonder whether Johnson, 58, would try to stage a comeback.

"Let me say that I am now like one of those booster rockets that has fulfilled its function and I will now be gently reentering the atmosphere and splashing down invisibly in some remote and obscure corner of the Pacific," Johnson said in front of the door of Number 10 Downing Street.

"Like Cincinnatus, I am returning to my plough."

Since being forced to announce his resignation as prime minister in July after just three years in office, Johnson and his team have been tight-lipped on what comes next for a man whose career has spanned journalism and politics, but one who is never long out of the public eye.

He has thrown his support behind his successor, Liz Truss, and one source who had worked closely with him for years said he would not cause trouble for her in parliament, quoting him as often saying "never haunt the brief".

RETURN?

Those closest to him say his resignation will allow him to no longer be "public property", signalling he will take a step back from the media circus that has followed him for decades.

But he will be keen to make money, said the source who has worked for him, and will most probably return to writing columns for newspapers which reward him with handsome yearly cheques, and could seek a seat on the board at a financial investment company.

He will also want to continue to help Ukraine after becoming one of its most vocal supporters since Russia's February invasion and could finish a book he was writing on Shakespeare which was due to be published in 2016.

But for most commentators, the big question is will he try to return as prime minister, something many expect from a man who according to one biographer as a child said he wanted to be "world king".

The jury is out, with one source saying it was unlikely. His popularity has also slumped, with polls suggesting a majority of voters thought he had done a bad job in Downing Street.

On Sunday, however, Edward "Eddie" Lister, who has been a close adviser for years and was his chief of staff for a brief time in 2020-21, said people should never write Johnson off when asked whether he could return to high office.

"Well, maybe in the future, I'd never say never on anything with Boris Johnson, anything is possible," he told Sky News.

"He is going to be watching all this and if something happens in the future, as you said, if the ball comes loose in the scrum, then anything could happen. I am not going to predict; all I am saying is I would never write him off."