How many Covid lockdown parties were held in Downing Street?

The prime minister is facing calls from some Conservative MPs to resign after he apologised for attending a drinks party in the Downing Street garden during the first lockdown.

Boris Johnson admitted attending the event but said he believed it was a "work event" which "could be said technically to fall within the guidelines".

Senior civil servant Sue Gray is investigating this and other parties at Downing Street.

This what we know - so far - about them:

15 May 2020: A photo showed the prime minister and his staff with bottles of wine and a cheeseboard in the Downing Street garden. When asked about it, Boris Johnson said, "those people were at work talking about work".

20 May: About 100 people were invited by email to "socially distanced drinks in the No 10 garden this evening" and asked to "bring your own booze!". Witnesses told the BBC the PM and his wife were among about 30 people who attended. Boris Johnson apologised for attending and said he had spent 25 minutes at the event, before returning to his office.

13 November: Sources told the BBC that Downing Street staff members attended a gathering with Carrie Johnson in the flat where she and the prime minister live. A spokesman for Mrs Johnson denied the party took place.

27 November: A leaving event was held for No 10 aide, Cleo Watson, where people were drinking, and Mr Johnson made a speech, according to sources.

10 December: The Department for Education confirmed it had an office gathering on this date to thank staff for their work during the pandemic. It said drinks and snacks were brought by those who attended and no outside guests or support staff were invited.

15 December: Multiple sources have told the BBC there was a Christmas quiz for No 10 staff on this date. A photo - published by the Sunday Mirror - showed Boris Johnson taking part and sitting between two colleagues. Number 10 said the prime minister "briefly took part virtually" to thank staff for their work during the pandemic and the two people were members of his closer staff who had come in to help him with the technology.

18 December: Downing Street originally denied a report by the the Daily Mirror that a party took place in Downing Street on this date. However, a video obtained by ITV News showed the prime minister's then-press secretary Allegra Stratton, joking about reports of an event, saying: "This fictional party was a business meeting and it was not socially distanced." Ms Stratton subsequently resigned.

16/17 April 2021: Two leaving parties took place separately in Downing Street, before merging and carrying on in the garden until after midnight. Boris Johnson did not attend and was at his official country residence, Chequers, at the time. This was on the eve of the funeral of the Duke of Edinburgh, at which the Queen sat alone, socially distanced from other members of her family. Downing Street has apologised, calling the parties "deeply regrettable... at a time of national mourning".