Queen Elizabeth resting after a day’s hospital stay

Britain's Queen Elizabeth, 95, was resting yesterday and undertaking light duties after she spent a night in hospital for the first time in years for what Buckingham Palace termed "preliminary investigations". 

The world's oldest and longest-reigning monarch stayed in hospital overnight on Wednesday but returned to her Windsor Castle home to the west of London the following day, with officials saying she was in good spirits and back at work.

The queen, who cancelled an official trip to Northern Ireland on Wednesday, had been told to rest by her medical staff, Buckingham Palace said, but her ailment was not related to COVID-19.

"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," the palace said late on Thursday.

Aides gave no details on what had prompted the medical attention, and some royal correspondents said they hoped the official version of events painted the full picture.

A royal source said the queen had stayed at the King Edward VII hospital in central London for practical reasons and that her medical team had taken a cautious approach.

British Prime Minister Boris Johnson's best wishes have been passed to Queen Elizabeth, his spokesman said.

The head of state, who next year celebrates 70 years on the throne, is known for her robust health. The last time she is thought to have spent a night in hospital was in 2013 when she was suffering from symptoms of gastroenteritis.