Duchess of Cambridge
WeirBros/Splash News Online
Call it tea with Kate and the in-laws.
The Duchess of Cambridge
will join her grandmother-in-law, Queen Elizabeth, and her stepmother-in-law, Camilla, the Duchess of Cornwall, at an official engagement at Piccadilly's flagship Fortnum and Mason's store on March 1, as "three royal ladies have tea," a royal source tells PEOPLE.
The tea party with the trio will serve as the centerpiece of an event to mark the regeneration of the London area of Piccadilly and be the first of two outings for Kate
is serving as a Search and Rescue helicopter pilot
in the Falkland Islands.
The second event, on March 8, will find Kate joining the Queen and Prince Philip on a field trip to Leicester.
Until then, Kate is scheduled to visit Liverpool Tuesday, to pay her respects at an alcohol-free bar connected to the charity Action on Addiction
and a children's hospital.