Buckingham Palace has remained tight-lipped over the Queen's bloodshot eye at a polo match in Windsor on Sunday.

While close-up video of the monarch showed her infected left eye, a Buckingham Palace spokesperson refused to explain the cause, only saying that "nothing untoward" happened and Her Majesty was in "fine fettle".

The Royal couple's appearance follows on from the Duke of Edinburgh's release from hospital a week ago after suffering a bladder infection during the Diamond Jubilee celebrations.

The Cartier Queen's Cup Final is one of the world's top five polo events, attracting celebrities and players from around the globe.