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
On Wednesday, a coroner will decide whether to open a full inquest into the 1974 Birmingham pub bombings which killed 21 people.
After 116 years of tailoring, over 1,000 jobs are set to be lost at fashion retailer Austin Reed.
Northern and Western areas keep best of sunshine in next few days.