03/07/2016 AT 12:10 PM EST
It's the painting Pitts!
Brad Pitt enjoyed an artistic outing with his two youngest children in London on Saturday.
Pitt, 52, who's currently in the British capital filming an as-yet-untitled World War II spy drama costarring Marion Cotillard, took Knox and Vivienne, 7, for a special pottery-painting treat in the cold winter sunshine – and even picked up a brush to make a creation or two of his own.
"It was just Brad and the twins doing the painting together," a source tells PEOPLE of the excursion, which happened a day before the U.K. celebrated Mother's Day. "They were in the pottery cafe for a couple of hours and seemed to have a lovely time. They were very happy."
The source added: "It wasn't a Mother's Day thing. Knox and Vivienne painted a few things and then Brad painted a few things himself. It was just a fun day out with Dad."
Earlier in the day, Brad was also spotted walking around west London with the twins and their eldest brother, Maddox. The Cambodian-born 14-year-old has recently been helping mother Angelina Jolie Pitt with some movie research for the real-life Cambodian drama First They Killed My Father, which Jolie Pitt co-wrote, produced and directed. His Vietnamese-born brother Pax, 12, also took on the role of set photographer.
Brad Pitt took three of his children along to a plate painting workshop in London on Saturday, ahead of Mothering Sunday.