The double Oscar-winner said the “old man” took her behind a door and asked her if she wanted a sweet before sticking his tongue in her mouth.

Thompson, 54, said that after the incident she felt guilty because she thought it was her “fault”.

Speaking out to highlight the dangers children face today with social media, she said: “My parents brought him to the house for my party. He was an old man with grey hair. And he took me behind a door and said, ‘Would you like a sweetie?’

“I said, ‘Oh, yes please,’ but I had a funny feeling. He gave me the sweet and said, ‘Will you give me a kiss?’ and I said yes. So I went up to kiss him on the cheek and he planted his mouth on mine, stuck his tongue in my mouth and wiggled it about. I thought it was my fault — children always think it’s their fault.”