I had set out from Shepperton at seven that morning, expecting to find a small location crew at the Sunningdale mansion. Rented by the film company, the house would play the part of my childhood home in Amherst Avenue. Much of the film had already been shot in Shanghai, where the banks and hotels along the Bund stood unchanged since the Communist seizure of the city in 1949. But the houses in Amherst Avenue were semi-derelict, turned into tenement apartments crammed with Chinese families and makeshift offices. No. 31 Amherst Avenue now contained the New China Electronic Import and Export Agency. Its drive was overgrown, its rotting window frames were supported by bamboo scaffolding, and the swimming pool had been roofed over to provide a damp-proof warehouse.

Fortunately, a reasonable replica of Amherst Avenue lay to hand on the other side of the world, a few miles from the studios at Shepperton. These handsome, half-timbered mansions, built in the 1930s beside the golf course, had served as the models for the houses which the British émigrés like my parents had built in the suburbs of Shanghai—houses whose Tudor exteriors were themselves façades, hiding American bathrooms, kitchens, and air conditioning.

There was something odd in the notion that the home of a near-neighbour could serve so plausibly as my childhood house, as if these Thames Valley towns formed part of Greater Shanghai. While I followed the studio van carrying the party of costumed extras I looked up at the familiar mullioned windows and realised how shrewd an eye the art director had brought to his job. He had convincingly re-created the exotic city of memory from materials far nearer to me than I cared to accept.

In place of the small location crew that I expected, a fleet of vehicles had taken over this quiet corner of Sunningdale. At first sight the scene resembled the evacuation of London—dozens of trailers sat in the surrounding fields, huge marquees stretched their canvas over miles of duckboard, double-decker coaches, restaurant buses, and lavatory trailers were parked in lines, generators drummed at the cold morning air, sending their current through a maze of cables to the location three hundred yards away. A private police force controlled the traffic, and a bus service ferried cast and crew from the trailers and makeup vans.

Not one house, I discovered, but four of the mansions had been rented by the film company, each contributing a segment of my childhood home—one provided a drained swimming pool, another the reception rooms and lawn where the fancy-dress party on the eve of Pearl Harbor would be held, while the third and fourth would re-create the kitchen, the dining room, and my own bedroom. Later that day, as I walked around the site, I stared through the windows of the mansions around the golf course, wondering what other segments of my childhood were hidden among the bridge tables and billiard rooms.