Prince Charles laughed as a well-wisher shouted to him, "Congratulations Sir, it's triplets!"
As the Prince walked over to say hello, John Dowson joked, "I heard it on the radio".
Mr Dowson said afterwards, "He just laughed, he was really jolly. Everybody's so excited in the country for him".
More top news
A weather warning is in place across the south-east with heavy rainfall expected. Elsewhere there will be plenty of sunshine around.
Britain's Lewis Hamilton will join an elite club of double Formula One champions if he can secure a top-two finish in Abu Dhabi today.
A naked man fell through the ceiling of a women's toilet at a US airport before fleeing and "viciously assaulting" an elderly man.