The easy way round buying books for children at Christmas is just to get them the latest David Walliams and have done with it. And indeed, Grandpa’s Great Escape (Harper Collins, £12.99), about the sympathetic friendship of a grandfather and grandson, is funny, productive of intergenerational goodwill and spikily illustrated by Tony Ross, though, as my son observed, it’s a pity so many nice people in Walliams’s books end up dead at the end.