The Prime Minister’s wife, Carrie Johnson, has paid a fixed penalty notice relating to her husband’s birthday bash in the Cabinet Room of No 10 during Covid lockdown.

A spokesperson for Mrs Johnson confirmed the former director of communications for the Tories paid the fine “relating to the gathering on the afternoon of June 19 2020” and that while “she believed that she was acting in accordance with the rules at the time”, she “apologises unreservedly”.

It is understood Mrs Johnson briefly attended the Cabinet Room with her newborn baby in her arms during her husband’s lunch break alongside some socially distanced staff and that because the fixed penalty notice was settled within 14 days, it was a reduced rate of £50.

The spokesperson said: “Mrs Johnson has paid a fixed penalty notice relating to a gathering on the afternoon of June 19 2020. Whilst she believed that she was acting in accordance with the rules at the time, Mrs Johnson accepts the Metropolitan Police’s findings and apologises unreservedly.”

Downing Street had admitted staff “gathered briefly” in the Cabinet Room on June 19 2020, in what was reportedly a surprise get-together for the Prime Minister organised by Mrs Johnson.

The PA news agency was told Lulu Lytle, the interior designer behind lavish renovations of the Downing Street flat, briefly attended while undertaking work there.

However, No 10 denied a report that, later the same evening, family and friends were hosted upstairs to celebrate the occasion.

It is not the only “partygate” event Mrs Johnson is linked to, though.

Mrs Johnson also reportedly hosted parties in the official flat over No 11 where she and her husband live, including one event on November 13, the night of Dominic Cummings’ acrimonious departure.

A spokesman for the Prime Minister’s wife called the claim “total nonsense” at the time it was reported.

However, reports have since suggested that the Prime Minister was seen heading up to the flat on the night in question, with the Mail On Sunday stating that Abba songs, including The Winner Takes It All, were heard coming from the residence.

Mr Cummings, former de facto chief-of-staff at No 10, has alleged there are photographs of parties held at the flat during lockdown and said he has spoken to people who heard music coming from the Johnsons’ accommodation on the night he left Downing Street.