Kate was merely delivering the kiss she auctioned at last year's event to help raise funds for Great Ormond Street Hospital. And judging by the huge smile on the recipient's face, it was worth every penny.
Mum-of-one Kate, whose daughter Lila Grace is six, was on vampy form at the bash in a black corset dress, Louboutins and a lick of red lipstick.
At one point she turned rock chick, grabbing the microphone during the musical entertainment and giving attendees an impromptu performance.
Kate's musician other half was among acts doing a turn on the night. Other guests included Kate's close pal Sadie Frost and Natalie Imbruglia.
Society beauty Tamara Beckwith was also in attendance, enjoying a night out with her Italian husband Giorgio Verona. The mum-of-two also stepped out in a black corset dress, though jazzed up her look with a colourful clutch.