“I spoke to Heathrow. They said this happens once every five years.”
Describing the victim, he said: “One of the reasons his body was so intact was because his body was an ice block.”
The Met Police said a post-mortem examination would be carried out in due course and the death was not being treated as suspicious.
Kenya Airways said the aircraft was inspected and no damage was reported.
A bag, water and some food were found in the landing gear compartment on the aircraft when it landed.
A spokesman for the airline said: “The 6,840km (4250-mile) flight takes eight hours and 50 minutes. It is unfortunate that a person has lost his life by stowing aboard one of our aircraft and we express our condolences.