On February 12, the couple, who are set to celebrate their fifth wedding anniversary this April, visited the Crown Inn pub in East Rudham, some six miles from their country home, Anmer Hall, in Norfolk.
Leaving 2-year-old Prince George and 9-month-old Princess Charlotte at home, they dined on pan-roasted Halibut steak and wild mushroom risotto, PEOPLE understands.
According to The Sun, which first reported the story, William, 33, sipped a glass of wine while Kate, 34, had sparkling water.
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"They were leaning into one another chatting away, laughing and joking," a pub regular told The Sun. (A pub staffer declined to comment.)
The cozy evening came at the end of a week when William is believed to have been largely carrying out his shifts as a helicopter pilot for East Anglian Air Ambulance.
On Sunday, Kate took a helicopter down to London and back for her engagement honoring the 75th anniversary of the Royal Air Force's Air Training Corps. She is patron and Honorary Air Commandant.
Next week, William and Kate will head back to their former home in North Wales, where the prince worked as a Royal Air Force search and rescue pilot. They are to watch a parade and attend a reception at his former base, RAF Valley, where personnel are marking the end of more than 75 years of RAF search and rescue operations.