In bed with Chile's torturers

Just before midnight on 16 October 1998, two London plainclothes policemen arrested an 82-year-old South American. The old man, who spoke almost no English, was on a private visit, having surgery at the London Clinic for a spinal hernia. And, like the typical wealthy tourist, he had done the sights: Madame Tussaud's, the National Army Museum, Fortnum and Mason. He had bought books about Napoleon at Foyles. The charges laid at his door, however, made it clear that General Augusto Pinochet, former dictator of Chile, was not your run-of-the-mill visitor. He was arrested for crimes against humanity, including torture, genocide and ordering disappearances.

Yet few Britons appeared to know who he was. Fewer still had any memory of the fact that, in September 1973, he had overthrown Chile's democratically elected socialist president, Salvador Allende, and presided over a regime that saw - according to official human-rights figures - some 2,095 people killed and a further 1,102 "disappeared". And hardly anyone had any idea of why he had come to Britain and why, most bizarrely, senior figures in the Tory opposition chose to speak out so volubly in his defence. It is this intriguing web that Guardian feature writer Andy Beckett sets out to unravel in Pinochet in Piccadilly, his first book.

Britain's "hidden history" with Chile, Beckett shows us, dates back to the start of the 19th century when Chile was angling for independence from Spain. Answering the call came adventurer Thomas Cochrane, 10th earl of Dundonald. His "liberation" of Chile was successful, and also opened up the country to capitalists, of whom the most vigorous were the British. This theme - "the use of force to clear the way for profit" - would find its most extreme adherent in Pinochet.

The first decades of the 20th century, however, saw a gradual drifting apart of Chile and Britain. Between 1900 and 1960, Beckett writes, Chile was "industrious, democratic and stable". It was not until the mid-1960s that - with the election of centre-Left president Eduardo Frei, an appealing figure for Harold Wilson - Britain's interest was reawakened. The climax of Chile's Left-wing experiment came in 1970, with the election of Allende who - to fierce US opposition - set about creating " better paid and unionised jobs" and more opportunities for poorer Chileans. But when Allende began to talk about the creation of a single-chamber parliament, the army rose up in revolt. Inflation started to rise; industrial output fell. Then came the coup.

Pinochet's brand of freemarket capitalism - whatever the human cost - would prove particularly alluring to Margaret Thatcher. By the mid-1970s, with Britain looking increasingly fragile, admiring Right- wingers looked towards Chile as an example of how to revive a moribund economy. Thatcher's election in May 1979 introduced Britain, Beckett writes, "to the harsh Chilean formula of economic shock treatment, cuts in the welfare state, privatisation and anti-trade union legislation". And, come the Falklands War, the relationship was so robust that Chile gave support to Britain in the form of communications, information and refuge for its armed forces, a fact publicly acknowledged by Thatcher during Pinochet's arrest.

In untangling this extraordinary story, Beckett combines travel writing, history and investigation. Of these, the travel writing is the least effective, with his descriptions often seeming redundant, or plain perplexing: what exactly is "a smart, muted-green jacket of the sort favoured by Santiago businessmen"? And what do "Jilly Cooper earrings" look like? But his journalistic digging is second to none. Interviewing 74-year-old Alan Walters, formerly Margaret Thatcher's economic adviser, he hears him casually brushing aside the brutalities of Pinochet's regime. "I knew that with revolutions of that kind you are going to get casualties. Obviously, nasty things went on." Every time Walters visited Chile during the 1980s, he would alert Thatcher to his plans. She would whisper: "Keep quiet about it. Don't advertise it."