Children's author Judith Kerr, who wrote The Tiger Who Came to Tea, has revived her cuddliest children's book character Mog the Forgetful Cat for the Sainsbury's Christmas TV advert. In Mog's Christmas Calamity, the bushy-tailed moggy sets in motion a string of disasters, yet manages to save the family from a fire. Kerr, 92, who wrote the semi-autobiographical When Hitler Stole Pink Rabbit about her childhood in 1930s Berlin, even makes a cameo, telling little Debbie Thomas that Mog "deserves a medal". To which the little girl replies: "I think she'd rather have an egg."

An illustrated book of the story is on sale in the supermarket chain with proceeds going to the Save the Children charity.