The name of the street where the Dursleys live is a reference to that most suburban plant, the privet bush, which makes neat hedges around many English gardens. I liked the associations with both suburbia and enclosure, the Dursleys being so smugly middle class, and so determinedly separate from the wizarding world. The name of their area is ‘Little Whinging’, which again sounds appropriately parochial and sniffy, ‘whinging’ being a colloquial term for ‘complaining or whining’ in British English.

Although I describe the Dursleys’ house as big and square, as befitted Uncle Vernon’s status as a company director, whenever I wrote about it I was unconsciously visualising the second house I lived in as a child, which on the contrary was a rather small three-bedroomed house in the suburb of Winterbourne, near Bristol. I first became conscious of this when I entered the number four Privet Drive that had been built at Leavesden Studios, and found myself in an exact replica of my old house, down to the position of the cupboard under the stairs and the precise location of each room. As I had never described my old home to the set designer, director or producer, this was yet another of the unsettling experiences that filming the Potter books has brought me.