The Duchess of Cambridge was a surprise guest at a charity event today, just days after she made her first public appearance since announcing her pregnancy and was 'bump-shamed' on social media for her svelte frame. Kate joined the Duke of Cambridge and Prince Harry at Paddington Station, where they met with children from the charities they support. The event, which was hosted by film production company StudioCanal, was also attended by the cast and crew from the forthcoming film Paddington 2, including the film's famous bear. It's not clear what the much-loved character said to Kate, but as her reaction suggests, the bear had a good sense of humour.Following a chat - and a quick twirl - with Paddington, the royals boarded the Belmond British Pullman train to speak to the youngsters taking part in the event, who had been selected by members of their Charities Forum. There are over 30 organizations involved in the Forum, which consists of charities that William, Kate and Harry work with as patrons and other organisations they support.The Duchess, who is in the early stages of her pregnancy with her third child, wore a pink and black dress, believed to be from Orla Kiely, which showed off the slightest sign of her baby bump. It's only her second appearance since the news of her pregnancy broke on 4 September, when Kensington Palace confirmed she was suffering from Hyperpremesis Gravidarum, a rare form of morning sickness. This has forced her to miss a number of recent engagements, including Prince George's first day at school, but Kate is now expected to return to work gradually in the coming months.