The royal couple was travelling back to Britain from an official visit to Denmark in November (11) when the pilot of a plane they were travelling in was forced to take emergency action to avoid crashing into another aircraft at London's Heathrow Airport.

A source tells Britain's The People, "This really was a serious incident and would have been terrifying for those on board. The aircraft ahead of them hadn't cleared the runway in time for the plane carrying the Duke and Duchess of Cambridge to land... The pilot took the decision to ascend suddenly ­during the approach and thankfully he was able to land safely."

A spokesman for British Airways confirmed the incident, but insisted safety procedures were correctly followed.

The representative says, "Our crew were told by air traffic control to perform a go-around - a perfectly ­standard ­operation with no safety ­implications - because an aircraft from another ­airline hadn't fully cleared the runway.

"Safety is always our ­priority and all our pilots are fully trained to deal with procedures of this kind. Our aircraft landed safely and ­customers left the plane as normal."