The Queen will carry out light duties as she continues to rest following her Wednesday night stay in hospital for “preliminary investigations”, it is understood.
A source said the situation was the same as Thursday, with the Queen “resting and undertaking light duties”.
The Queen could be working on correspondence from her red boxes – policy papers, Cabinet documents, Foreign Office telegrams, a daily summary of events in Parliament, letters and other State papers.
The famous boxes are sent to the monarch by her private secretaries wherever she is every day of the year.
The head of state’s trip by car rather than helicopter to central London’s private King Edward VII’s Hospital was kept a secret but the Palace issued a statement on Thursday evening after The Sun newspaper broke the news.
It was the monarch’s first overnight stay in hospital since she spent a night at the private clinic in 2013 when she was treated for the symptoms of gastroenteritis.
A Buckingham Palace spokesman said late on Thursday night: “Following medical advice to rest for a few days, the Queen attended hospital on Wednesday afternoon for some preliminary investigations, returning to Windsor Castle at lunchtime today, and remains in good spirits.”