The victim is believed to have sneaked on to the British Airways jet before it took off from Johannesburg bound for Heathrow. His body was found on the offices of online marketplace Notonthehighstreet.com, on a busy road beneath the flight path in Richmond.

A second man survived the journey and was taken to hospital in a serious condition. The 24-year-old is believed to have been found unconscious in the undercarriage of the plane at Heathrow shortly before the dead man's body was discovered.

Flight data revealed that the Boeing 747 would have been flying over Richmond, in south-west London, at an altitude of around 1400 feet as it approached the runway at the end of an 11-hour journey.

A Scotland Yard spokeswoman confirmed that police had been called to the office block at 9.35am on Thursday following the discovery of the body. The first suspected stowaway had been found at Heathrow at 8.28am.

A British Airways spokeswoman said: "We are working with the Metropolitan police and the authorities in Johannesburg to establish the facts surrounding this very rare case."