The Queen has been admitted to hospital for the first time in 10 years after being diagnosed with gastroenteritis. A spokesperson for the royal family said the 86-year-old was taken by car to King Edward VII Hospital in London, the same hospital that treated the Duchess of Cambridge in December.
All of the monarch's upcoming engagements, including her trip to Rome with The Duke of Edinburgh, have been cancelled and some will be rescheduled when the stomach inflammation is gone and she is back to full health.
Despite the absence of their royal guest, organisers in Swansea still went ahead with their planned parade to Swansea's Guildhall, with Lord Lieutenant of West Glamorgan, Byron Lewis, taking over the Queen's ceremonial role.
The Queen is expected to spend around two days in hospital.
Buckingham Palace said the action is just a precautionary measure as it will be easier for doctors to monitor the Queen's condition in the London hospital.
Over her 60 years as Britain's sovereign the Queen has rarely cancelled her engagements due to ill-health and the last time she was in hospital was in 2004 for a knee operation.
News of the Queen's illness came on Saturday when she was forced to cancel her visit to the Welsh city of Swansea where she was due to present leeks to members of the 3rd Battalion to mark St David's Day. As the result of her illness the Queen spent the day recuperating at Windsor Castle. While she rested officials decided it was safer for her be in hospital.
The Queen's illness follows her appearance at Buckingham Palace on Thursday where she presented honours to a number of Britain's 2012 Olympic winners including Jessica Ennis, Nicola Adams and Joanna Rothswell.