Prince William's cheeky weed jokes during tour of Heathrow Airport

Prince William, Duke of Cambridge talks to Royal Mail sorting office workers during a visit to the Royal Mail international distribution centre. Photo / Getty Images

Prince William toured the Royal Mail logistics centre at Heathrow Airport to learn about wildlife trafficking but the conversation ended up going in a completely different direction.

The Duke of Cambridge was surprised by the overpowering smell of illegal cannabis coming from a room full of the drug.

He joked that there was "quite a good, strong smell" during his tour at Heathrow Airport.

He was visiting the centre as part of his work with the charity United For Wildlife, and was shown around the depot full of illegal drugs, weapons and wildlife which had been seized from passengers entering the country.

Border Force officer Steve Harrington asked the Royal to "excuse the smell" when they walked in.

"It's quite a good strong smell," the Prince replied.

"We had better get out before we have a drugs test."

Harrington explained that the "large seizures of cannabis" come from "the United States, where it is legal in some states".

The Prince was also told about the 1657 weapons that were captured being smuggled into the UK in the past four weeks alone.

"That is a staggering amount of weapons in one month. That is quite shocking," he said.

Prince William was also shown four wildlife packages which have been seized this week, including the snakeskin of a rock python.

"I would not like to have met the snake wearing that," he said.