Queen Elizabeth II has returned home to Windsor Castle after undergoing medical checks in hospital this week.

The 95-year-old monarch returned to her residence after visiting a private hospital in central London at lunchtime on Thursday and is "in good spirits", according to a statement from Buckingham Palace officials.

She had cancelled a scheduled visit to Northern Ireland due to the health scare after being given medical advice to rest for a few days.

"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," a representative commented.

The British sovereign was taken by car to King Edward VII's Hospital in Marylebone where she was seen by specialists. Her hospitalisation is understood not to be due to Covid-19.

She was kept in hospital overnight for "practical reasons" but was back at her desk undertaking light duties on Thursday afternoon. Her hospital visit is her first for medical reasons since 2013, when she was suffering from gastroenteritis.

Her husband, Prince Philip, passed away at the age of 99 in April, with his cause of death given as "old age".