Speaking at a Downing Street press conference, Mr Johnson said: "I know that everybody will be wanting to offer their best wishes to Her Majesty the Queen and I just wanted to reassure everybody by saying that I did see the Queen for an audience last week on Wednesday in Windsor and she's very well.

       "It shouldn't need saying but I just wanted to say it anyway."

       The news comes after the Queen missed several other key events, including the Festival of Remembrance at the Royal Albert Hall on Saturday evening.

       Royal staff who worked for Meghan Markle and Prince Harry have been told not to delete any correspondence amid the Duchess's privacy battle, according to reports.

       Court of Appeal judges are considering whether to overturn the decision earlier this year to grant summary judgment to the Duchess of Sussex on her privacy and copyright claims. Emails and texts messages sent within Kensington Palace and Buckingham Palace, between palace staff and the Royal Family, could be searched and included in documents at a future trial.

       The Telegraph reports that it is understood staff who worked for the Sussexes have been instructed not to delete any correspondence should searches need to take place.

       This week, explosive evidence emerged as messages between Meghan and her former press secretary Jason Knauf were heard at the court.

       Mark Stephens, a media law expert and partner at Howard Kennedy, said it was likely emails and texts between members of staff would be searched and produced in court if the case moved to a full trial.

       He told the Telegraph: “It’s almost certain that masses of that material is going to have to be searched to look for relevant material."

       But he added: “I think it’s almost a racing certainty that whilst it will be handed over the Mail on Sunday’s lawyers, the judge might put in place reporting restrictions to prevent it being used in news reporting.”

       It is part of the process for any party in any court case to be instructed not to delete documents and correspondence.

       Additional reporting from Brian McGleenon.

       FOLLOW BELOW FOR LIVE UPDATES ON THE ROYAL FAMILY: