Lunch was on the Duke and Duchess!

Prince William and Kate Middleton hosted 27 members of their staff on Tuesday Dec. 18 for a Christmas party and lunch at the Bumpkin restaurant in London's Notting Hill neighborhood, a source confirms to Us Weekly.

Celebrating with members of the Household Cavalry, their press team, private secretaries and other staffers present, Kate and William, both 30, dined at a private room at the eatery -- right beneath a portrait of Her Majesty, Queen Elizabeth II!

PHOTOS: Royal pregnancies

Clad in a floral blue and white dress with a dinner jacket, the pregnant Duchess "sipped soft drinks," the source says, adding that her "health is improving" after dealing with acute morning sickness earlier this month.

PHOTOS: Kate's style evolution

And, as is usually the case with the spouses, the private bash wasn't extravagant, with everyone eating from the price-fixe Christmas Turkey menu, which cost a humble 30 pounds, or approximately $48, a head.

PHOTOS: William and Kate's first year of marriage

It's the second known outing in the past few days for the pregnant Duchess, who looked radiant and still quite slim in a green Alexander McQueen gown at the BBC Sports Personality of the Year ceremony Dec. 16 -- telling former soccer player Gary Lineker that she's feeling "very well."

This article originally appeared on Kate Middleton, Prince William Host Christmas Lunch for Staff at Restaurant