Every now and then, a public speaker uses a phrase that perfectly sums up the mood of the time – “the People’s Princess”, for instance, or maybe, who knows, “Bottler Brown”. In 1946, when Churchill made his famous remark in Fulton, Missouri that an iron curtain had descended across Europe, he may have been slightly ahead of his time. No longer prime minister, his remarks about a recent ally were condemned by both the British government and President Truman. But the metaphor was a good one and it stuck. So much so that I remember as a child insisting to my classmates that the iron curtain was the only man-made structure visible from outer space. It’s a miracle the Great Wall of China never sued.

Churchill may have been the first to hit rhetorical paydirt with the expression but he wasn’t the first to use it (Goebbels used it at least twice in 1945 – not the sort of pedigree Churchill would be keen to acknowledge). In this sprightly and readable book, Patrick Wright sets out to trace the history of the phrase from Fulton back to the original, literal “iron curtain” that the playwright Sheridan had included in his Drury Lane Theatre of 1791 to protect it from fire (the theatre burnt down in 1809).

This is a risky strategy for a historian. What if the only people to utter the expression were thunderous bores who spent the rest of their lives in a shed counting pebbles? But Wright’s raw material doesn’t disappoint: among his subjects are the incredibly articulate first-world-war pacifist Vernon Lee (née Violet Paget), who wrote of “War’s monstrous iron curtain”, this “barrier of otherness” cutting her off from Germans sitting, like her, in a church at Christmas listening to Bach (Bach being, we presume, the cultivated lady equivalent of the football match in no-man’s land); and Elisabeth, Queen of the Belgians, a sort of great-war Princess Di meets Florence Nightingale, the very embodiment of her small country’s tremendous bravery in the face of the “merciless Hun”, who had to place an “iron curtain” between herself and her family because she was actually born a German princess (whoops).

Wright really hits his stride when the “iron curtain” moves east from Germany after the first world war and is repositioned in front of the nascent Soviet Union, a policy that Churchill described at the time with a candour so sadly lacking in contemporary politicians as “Kiss the Hun, kill the Bolshie”. The curtain itself took various forms – armed blockades, cordons sanitaires of smaller nations – as the western powers tried to protect themselves from the “Bolshevik baboon” (Churchill again. Never knowingly understated).

What so distressed pacifists such as Lee was that once a curtain has come down, it’s impossible to see what’s happening on the other side and the propagandists can have a field day. Early Soviet workers were amazed that visiting westerners had already witnessed the effects of electricity, while many in the West were convinced Lenin had abolished marriage and nationalised every Russian woman. Into this early cold-war maelstrom sailed various union delegations and diplomatic missions, determined to seek the truth about the Bolshevik enterprise: groups such as the British Labour delegation of 1920, whose pilgrimage into the Promised Land of Socialism had to be regrettably curtailed for “internal digestive reasons”.

The travellers that remained, the ones with the stronger stomachs, would find themselves trapped by their hosts in an artificial bubble of plenty, full of smiling, happy socialists: prisoners in armchairs, shop windows crammed with luxury chocolates “every bit as good as Terry’s” an hour before the visitors’ arrival, pig farms where half-starved swineherds had been hastily replaced by “comely office girls” (although my own experience of comely office girls makes me wonder just how convincing they could have been). Only occasionally would a visitor glimpse the harsher reality “backstage”.

Theatrical metaphors apply themselves easily to the Soviet Union of show trials and parades, where every citizen had to act a role to survive. But the great strength of Wright’s quietly inspiring book is that it hums with contemporary relevance. In a polarised world of “us and them”, those who spoke of an iron curtain before Churchill were generally making a stand against the prejudices of the age (I think we’ll have to call Goebbels an exception). Whether it’s iron curtains or axes of evil, Bolshevik show-farms or media-manipulation, the phrases remind us to look beyond the “barriers of otherness” around us and see the people on the other side.

Iron Curtain: From Stage to Cold War by Patrick Wright

OUP £18.99 pp488

Available at the Books First price of £17.09 (including p&p) on 0870 165 8585

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