Former British prime minister Boris Johnson compared himself to a "booster rocket" jetting off into distant lands as he delivered his farewell speech outside No 10 Downing Street.

He has now tendered his resignation to Queen Elizabeth, handing over power to Liz Truss after his tenure, dominated by Brexit and Covid, was cut short by scandal.

Mr Johnson, who was forced to quit after losing the support of dozens of his ministers, flew to Scotland to see the 96-year-old monarch.

He and his wife Carrie spent almost 40 minutes with the queen before leaving Balmoral a few minutes before midday.

Boris Johnson and his wife Carrie outside Number 10

A statement from Buckingham Palace confirmed the British monarch had accepted his resignation.

"This is it folks", Mr Johnson earlier told politicians and media gathered outside the famous black door of Number 10 after he emerged with his wife Carrie this morning.

He was applauded by the assembled Tory MPs and officials as he approached the podium.

Mr Johnson said: "This is it folks. Thank you everybody for coming out so early this morning. In only a couple of hours I will be in Balmoral to see Her Majesty the Queen and the torch will finally be passed to a new Conservative leader.

"The baton will be handed over in what has unexpectedly turned out to be a relay race. They changed the rules halfway through, but never mind that now."

There was laughter from onlookers as Mr Johnson compared himself to a "booster rocket" jetting off into distant lands as he resigned his post.

"I'm now like one of those booster rockets that has fulfilled its function. I will now be gently re-entering the atmosphere and splashing down invisibly in some corner of the Pacific."

Cars carrying Boris Johnson depart Balmoral Castle after his resignation as British Prime Minister

The outgoing prime minister hinted that he intends to fade quietly into the background for now, comparing himself to Cincinnatus, a Roman statesman who - according to legend - returned to his farm after triumphing in battle.

Mr Johnson also said if his dog Dilyn and Larry the cat can "put behind them their occasional difficulties", then so can the Tory party.

He said: "Thank you everybody who's helped look after me and my family over the last three years, including Dilyn the dog.

"I just say to my party if Dilyn and Larry can put behind them their occasional difficulties, then so can the Conservative Party."

Ms Truss will become the next UK prime minister after being formally invited by the queen to form a government.

The former UK prime minister will be able to claim up to £115,000 (€133,000) a year to run his office when he steps down.

Mr Johnson's official spokesman indicated that he will claim the public duty costs allowance in relation to his continuing work as a former premier.

Media gathered outside 10 Downing Street, London this morning

The scheme was originally introduced following the resignation of Margaret Thatcher in 1990 to support ex-prime ministers who remain active in public life after they leave office.

It is meant to cover office and secretarial costs arising from their special position and does not apply to their private or parliamentary duties.

Asked if Mr Johnson would receive the allowance, his spokesman said: "I believe so. It certainly will be available to him."

However, the spokesman declined to be drawn on whether Mr Johnson would claim his ministerial severance pay of £18,860 - three months of his prime ministerial salary of £75,440, which he gets on top of his MP's pay of £84,144.

"It's not a question I've asked him. It would be available to him in the normal way."