Katy wearing a beautiful white lace dress and looking very gorgeous, she joined the company of business associates having dinner in the garden.
The recently single singer "was all smiles and in great spirits," an onlooker tells PEOPLE. "She had hellos for everyone at the table. She was adorable and spoke to them in a character-like cutesy voice before making her exit about five minutes later."
Things were calm for Tom Hardy, who was also at the Soho House the same Wednesday evening.
The Dark Knight Rises actor was spotted "having a nice time with a small group of friends around the bar area," an onlooker says. "He was chatting away and listening to stories while he sipped on a cocktail."
"He looked like he was enjoying a very low-key night out," the source adds.