The novelist and film-maker discusses his new novel The Last Word, a wickedly funny and incisive take on literary celebrity and the nature of the artist; and his latest film Le Weekend, his fourth collaboration with director Roger Michell. ‘The films were mostly concerned with a subject we believed was neglected in the cinema, the lives and passions of older people, whose anxieties and desires, we found, were as intense, if not more significant, than those of the young.’