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.
For no very good reason, I have never been fond of the number four, which has always struck me as a rather hard and unforgiving number, which is why I slapped it on the Dursleys' front door.
Measurements
Just as British witches and wizards do not use electricity or computers, they have never turned metric. They are not governed by the decisions of the Muggle government, so when the process of metrication (switching to metric measurements) began in 1965, witches and wizards simply ignored the change.
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Witches and wizards are not averse to laborious calculations, which they can, after all, do magically, so they do not find it inconvenient to