West Hampstead’s Jim Carter and Imelda Staunton switched on the Fortune Green Christmas lights on Saturday evening, as hundreds gathered to see the tree lit-up.
There were performances by Beckford Primary School's choir as the crowd enjoyed mince pies and mulled wine.
Mr Carter, best known for playing butler Carson in Downton Abbey and starring in films including Brassed Off, referenced his wife's role as an antagonist in Harry Potter and said: "Well done kids for standing so close to Dolores Umbridge."
Ms Staunton, one of Britain's best-known actors, following roles in hits such as Vera Drake, Pride and Sense and Sensibility, praised their singing, saying: "I think you will find that Fortune Green has got talent."
The children sang the Bugs Bunny Overtune, and Skelton Stomp, before the crowd joined in with Ding Dong Merrily on High and White Christmas.
Jackie Spreckley, from the Friends of Fortune Green who organised the event, thanked Dutch and Dutch and Paramount for sponsoring the tree, and Waitrose, Tesco Express and the Green Room for supporting the event with food and drink.
Speaking to the Ham&High afterwards, Mr Carter said: "It's what makes a community isn't it. You see the kids and the families out. I don't know if this is happening all over London, but West Hampstead feels like a village and this is a village event."
Ms Staunton said: "It's nice to be asked and to be included in it. I think, because, we do our own shopping, we do go out of the house and I think people know we're approachable and that we value this sort of life.
Mr Carter added: "Even if we weren't turning on the lights, we would probably be here drinking the mulled wine and eating the mince pies. So it's lovely. We are always happy to support local events. It's a great turnout."
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