Tables for the dinner were set up around 'Dippy' the dinosaur - the museum's famous Diplodocus skeleton.
While talking to guests, Kate revealed two-year-old George, loves sculpture.
The Daily Mail reports, Nicky Wilson, from Jupiter Artland in West Lothian, said: ‘The Duchess said George comes here a lot. We were talking about children interacting with sculpture and contemporary art and he loves doing that.
‘He loves 3D three dimensional sculptures. He does come here [the NHM] quite often.’
Former culture secretary Lord Chris Smith, chairman of the Art Fund said, ‘It was the first time I had met the Duchess and she was utterly charming. She is an art-lover and recognises the importance of museums, both as a resource and their importance to young people.
‘It's fantastic to have her presenting the Art Fund for this year and supporting the great work of all these museums.’