George Bush's favourite role model is, famously, Jesus, but Winston Churchill is close behind. The US president - who was yesterday again comparing the struggle in Iraq with the allies' efforts in the second world war - admires the wartime prime minister so much that he keeps what he calls "a stern-looking bust" of Churchill in the Oval Office. "He watches my every move," Bush jokes. These days, Churchill would probably not care for much of what he sees.

I thought a great deal about Churchill while working on my book Troublesome Young Men, a history of the small group of Conservative MPs who defied Neville Chamberlain's policy of appeasing Hitler, forced Chamberlain to resign in May 1940, and helped make Churchill his successor. I thought my audience would be limited to second world war buffs, so was pleasantly surprised to hear the president has been reading my book. He hasn't let me know what he thinks, but it's a safe bet that he's identifying with the portrayal of Churchill, not Chamberlain. I think Bush's hero would be bemused; parallels do leap out - but between Bush and Chamberlain, not Bush and Churchill.

Like Bush, and unlike Churchill, Chamberlain came to office with almost no understanding of foreign affairs or experience in dealing with international leaders. None the less, he was convinced that he alone could bring Hitler and Mussolini to heel. He surrounded himself with like-minded advisers, and refused to heed anyone who told him otherwise. In the months leading up to war, Chamberlain and his men saw little need to build a strong coalition of European allies to confront Nazi Germany - ignoring appeals from Churchill and others to fashion a "grand alliance".

Unlike Bush and Chamberlain, Churchill was never in favour of his country going it alone. Throughout the 1930s, while urging Britain to rearm, he strongly supported using the League of Nations - the forerunner of the United Nations - to provide smaller countries with one-for-all and all-for-one security. After the league failed to stop fascism's march, Churchill was adamant that Britain must form a true partnership with France and even reach agreement with the despised Soviet Union, neither of which Chamberlain was willing to do.

Like Bush, Chamberlain laid claim to unprecedented executive authority, evading the checks and balances supposed to constrain the office of prime minister. He scorned dissenting views, inside and outside government. When Chamberlain arranged his face-to-face meetings with Hitler in 1938 that ended in the catastrophic Munich conference, he did so without consulting his cabinet. He also bypassed the House of Commons, leading Harold Macmillan, a future Tory prime minister and then an anti-appeasement MP, to complain that Chamberlain was treating parliament "like a Reichstag, to meet only to hear the orations and to register the decrees of the government".

As was true of Bush and the Republicans before the 2006 midterm elections, Chamberlain and his Tories had a large majority in the Commons, and, as Macmillan noted, the prime minister tended to treat parliament like a lapdog legislature, existing only to do his bidding. "I secretly feel he hates the House of Commons," wrote one of Chamberlain's most fervent parliamentary supporters. "Certainly he has a deep contempt for parliamentary interference."

Churchill revered parliament. He considered himself "a child" and "servant" of the Commons and strongly believed in the legislature's constitutional role to oversee the executive. In August 1939, when Chamberlain rammed through a two-month parliamentary adjournment just weeks before the war, Churchill - still a backbencher - exploded with anger, calling the prime minister's move "disastrous", "pathetic" and "shameful". He encouraged anti-appeasement colleagues to mount similar attacks, and when Ronald Cartland called Chamberlain a dictator to his face, Churchill congratulated Cartland with an enthusiastic: "Well done, my boy, well done!"

Likewise, Churchill almost certainly would look askance at the Bush administration's years-long campaign to shut down public debate over the "war on terror" and the conflict in Iraq - tactics markedly similar to Chamberlain's. Like Bush and his aides, Chamberlain intimidated the press, restricted journalists' access to sources and claimed that anyone who dared criticise the government was guilty of disloyalty and damaging the national interest. Just as Bush has done, Chamberlain sanctioned the wiretapping of citizens without court authorisation; Churchill was among those whose phones were tapped.

Churchill also believed firmly in the need to protect individual liberties from government encroachment. That's not to say that he was never guilty of infringing them. In June 1940, when a Nazi invasion seemed imminent, he ordered the internment of more than 20,000 aliens, mostly refugees from Hitler's and Mussolini's regimes. But as the invasion scare abated, the vast majority were released, also by his order. "The key word in any understanding of Churchill is the simple word 'liberty'," wrote Eric Seal, his principal private secretary. "He ... reacted violently against all attempts to regiment ... opinion."

I've discovered that writing about Churchill and Chamberlain is like a Rorschach test. Readers draw parallels between the events of the 30s and today, according to their own political philosophies. I've received congratulations from people who see similarities between US woes in Iraq and Chamberlain's disastrous conduct of the so-called phony war in 1939-40. But I've also had fan mail from readers who favourably compare the Tory rebels' courageous fight against Chamberlain to the Bush administration's campaign against those opposing the Iraq war. Among those who've written to me in praise of the book are outgoing Bush adviser Karl Rove and Howard Wolfson, the communications director of Hillary Clinton's presidential campaign.

The president no doubt has his own Churchill. "He was resolute," Bush has remarked. "He was tough. He knew what he believed." But Churchill would snort, I believe, at the administration's equation of "Islamofascism", an amorphous, ill-defined movement forced to resort to terrorism by its lack of military might, with Nazi Germany, a global power that had already conquered several countries before Churchill took office. Still, key members of the Bush administration have compared critics of the war on terror to the appeasers of the 30s, equating their boss and themselves with Churchill and the "troublesome young men" who helped bring him to power. During bleak days in Iraq, the administration's hawks can be forgiven for hoping that history will show them to be as far-sighted about a gathering storm as Churchill was in the 1930s.

He believed that the US and Britain had a responsibility to serve as exemplars of democracy for the rest of the world, and both countries had to do their best to ensure that the "title deeds of freedom" were strongly safeguarded within their own boundaries. "Let us preach what we practise," he declared in his 1946 "iron curtain" speech in Fulton, Missouri. "But let us also practise what we preach."

· Lynne Olson is a former White House correspondent for the Baltimore Sun

contact@lynneolson.com

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