The Queen has been shown how to use a self-service check-out during an event in central London today. Her Majesty was being shown around a replica of the original Sainsbury's convenience store in Covent Garden and even cut the birthday cake as part of celebrations to mark the British supermarket chain's 150th anniversary Report by Chinnianl. Like us on Facebook at http://www.facebook.com/itn and follow us on Twitter at http://twitter.com/itn