The Duchess of Cambridge was casual in black skinny ankle grazer jeans, a black puffer jacket with contrasting white sleeves, and New Balance trainers.
Onlookers said Kate was in a great mood and smiled at people who recognised her.
Meanwhile hubby Prince William was busy joining a group of new dads at Future Men charity.
Earlier that week, the 37-year-old mum of three opened up about the struggles of parenting, admitting she was "very naïve" as a first-time mum.
