Staff at a Little Chef have said it was an honour to have the Duke of Edinburgh drop in to their cafe.
Philip called at the Doncaster branch of the roadside restaurant chain, which is on the A1, just north of the South Yorkshire town, with security guards and other staff.
Manager Celia Morrell said one of her staff asked him if wanted a table but he politely refused, saying he just wanted to stretch his legs as his staff bought take-away coffee and snacks.
Ms Morrell, 52, said the restaurant was busy at the time and she did not realise who it was at first - and neither did her young colleague.
"It was really exciting and also an honour that they'd picked our Little Chef to come and visit," she said.
"There was quite a large group of them and they were in the take-away area. Prince Philip was wandering around and o ne of the girls went up and asked him if he would like a table.
"She's only a young girl and she didn't realise who he was.
" He said 'Oh no, I'm just stretching my legs' and he wandered around a bit more.
"The security people were buying drinks and chocolates."
Ms Morrell said the girl who spoke to him did not spot who their VIP guest was until she returned.
"I said to her 'do you realise who that was?' and she was amazed when I told her."
The duke and his people arrived at the restaurant at about 11.30 to noon on Thursday, last week.
According to reports, he stopped off en route to a private engagement - a carriage-driving event in Cumbria.
Ms Morrell said: "It was real honour to have him here.
"There were lots of customers here at the time and some of them were getting very excited. Some were asking whether he was going to order one of our royal breakfasts."
The Little Chef's royal breakfast costs £10.99. It is the chain's standard Olympic breakfast topped off with a 6oz sirloin steak.
Ms Morrell, who has worked for Little Chef for 19 years and at the Doncaster branch for nine years, said the duke did not buy anything but she said it was possible one of the drinks and some of the snacks bought by his staff could have been for the royal visitor.
"I don't think he carries money, does he?" she said.
She said recalled that she once served the Earl and Countess of Wessex at the Little Chef in Selby before they were married.
The 93-year-old spent about 15 minutes at the roadside restaurant, which is next to a petrol station on the busy dual carriageway.
This is not the first time the Doncaster Little Chef has hit the headlines.
In 1991, then prime minister John Major famously stopped for a fry-up at the cafe - which was then branded as a Happy Eater - on his way to the Young Conservatives' conference in Scarborough.