Before Mr. Johnson’s return to work on Tuesday, any “important decisions” will be made by Mr. Johnson’s deputy, Dominic Raab.

According to Downing Street, Boris Johnson is recuperating after undergoing a small operation while short under deep anesthesia.

The official spokeswoman for the prime minister stated that Mr. Johnson entered a hospital in London around 6 a.m. on Monday for a regular sinus procedure covered by the NHS.

He returned to Downing Street soon before 10 a.m., according to the spokeswoman.

Number 10 stated that both Mr. Raab and Cabinet Secretary Simon Case were aware of the situation. The operation had been “planned for some time.”

In 2020, it was not believed that Mr. Johnson’s sinus condition was related to his COVID sickness.

Mr. Raab stood in for the prime minister at the height of the pandemic when he was hospitalized in intensive care.

Later, the deputy prime minister revealed to the Conservatives’ virtual party conference that he thought Mr. Johnson may have perished.

Regarding Mr. Johnson’s most recent hospitalization, Downing Street refused to disclose if he was on a waiting list.

The Commonwealth Heads of Government conference is taking place in Rwanda this week, and he is still scheduled to attend.

Chris Bryant, a Labour MP, tweeted, ostensibly in response to the procedure and the lengthy wait times for other NHS patients, “Have routine operations cleared their backlog?”

According to Downing Street, Mr. Johnson’s surgery “went well” and he is “delighted to be back in No. 10.”

Tuesday morning, the prime minister will preside over a Cabinet meeting, according to his official spokesperson.