He was used to giving wellattended performances at illustrious venues: during the past few years the 42-year-old musician had become an international celebrity. A frequent guest of kings and presidents, he had come to Britain to perform for the Prince of Wales. For today’s outdoor concert, however, there were no tuxedos or ball gowns, no flutes of champagne.

Behind Rawicz rose 45 neat, Edwardian boarding houses, each of their windows painted a shade of dark blue. In front, on a crescent of wooden chairs, sat a line of army officers. Behind them, in untidy rows on the grass, sat hundreds of refugees. Beyond the audience, the pianist could see Douglas harbour where boats chugged; in the middle distance, a palisade of barbed wire.

This marked the boundary of what was now known as “P camp”, or “Hutchinson”, an internment camp that housed many of Europe’s most brilliant minds – luminaries from the worlds of art, fashion, music and academia – who made up one of history’s unlikeliest prison populations.

Hutchinson camp opened on July 13, 1940, one of several internment facilities on the Isle of Man. Eventually, ten were established there to house thousands of German Austrian and Italian passport holders living in Britain, who, from May 1940, were arrested in a country gripped by spy fever.

That month, rumours abounded that Nazi sympathisers posing as asylum seekers in the Netherlands had assisted the German occupation. With the news from Holland, however, British newspapers began to call for mass internment.

“You fail to realise,” G Ward Price wrote in the Daily Mail, “that every German is an agent.” Most refugees spoke thickly accented English, were unaccustomed to British social norms and would make ineffectual spies. This didn’t seem to matter. As the politician Herbert Delaunay Hughes wrote at the time: “It is lamentable how quickly people seem to have forgotten who exactly the refugees are and how it is that they came to this country.”

When Hitler learned of Churchill’s internment policy, he reportedly gloated: “The enemies of Germany are now the enemies of Britain too. Where are those muchvaunted democratic liberties of which the English boast?”

” Most British citizens acknowledged the injustice inherent in mass internment but felt it was nevertheless a justifiable measure. The Home Secretary, John Anderson, was opposed to it, a position he hoped to hold, he wrote, “unless the war begins to go bad”.

But now, with the risk of a German invasion appearing not only likely but imminent, the new Prime Minister, Winston Churchill, ordered the arrest of the so-called “enemy aliens”, even those who had lived peacefully in the country for decades. Chaotic and sometimes cruel arrests followed, including those of thousands of Jews who had fled Nazi Germany only to be imprisoned by the people in whom they had staked their trust – a nightmarish betrayal.

Status provided no protection. Cambridge dons were arrested in a university-wide round-up of international students and professors, as were scores of artist refugees who had settled in north London.

The police arrested Emil Goldmann, a 67-year-old professor from the University of Vienna, in the grounds of Eton College. Rawicz and his performing partner, Walter Landauer, were detained in Blackpool, where they had just begun a run of revue performances in the Grand Theatre. Each of the camps on the Isle of Man had its own character. Peveril Camp, which housed British fascists and members of the IRA, was said to be boisterous and threatening.

Hutchinson, by contrast, was filled with academics and writers, painters and poets, actors, and sculptors. Inmates included the journalist Heinrich Fraenkel, who wrote and published a book, Help Us Germans To Beat The Nazis, from inside the camp, and Professor Gerhard Julius Bersu, a world expert on Vikings. There was the music critic Rudolf Kasztner, and the publisher Walter Neurath, who, following his release, founded the publishing company Thames & Hudson with the wife of his Hutchinson colleague, Wilhelm Feuchtwang.

THE CAMP was also home to more than 20 eminent artists, including Paul Hamann, a sculptor who had made life-masks of well-known English figures, including Winston Churchill’s wife Clementine; Ludwig Meidner, considered by many to be the greatest of all German Expressionists; and Kurt Schwitters, the pioneering Dadaist artist derided as degenerate by Adolf Hitler. Established artists provided training to aspiring young painters such as Peter Fleischmann, who later graduated from the Royal Academy of Art as Peter Midgley. As such, Hutchinson became known as “the Artists’ Camp”.

With such a high number of geniuses, the extraordinary inevitably occurred. Shortly after the camp opened some men emerged from their boarding houses carrying chairs and ladders which they set up around the terraced lawn. They beckoned passers-by, and, when they had a small crowd, began to hold forth on their specialist subjects.

Soon the lawn was filled with speakers and their various audiences, like, as one observer put it, a scene from Ancient Athens. A listener could wander freely between subjects, from Greek philosophy to explorations of the industrial uses of synthetic fibres to analysis of Shakespeare’s Sonnets.

Before he transferred to Hutchinson, Bruno Ahrends, an architect who designed Berlin’s highly influential modernist housing estates, had organised lessons for schoolboys in a previous transit camp.

Recognising the illustrious group of teachers in the camp, Ahrends approached its commandant, a former advertising executive named Captain Hubert Daniel, and requested permission to organise a formal schedule of lectures.

Daniel, known as “Danny” to his friends, offered Ahrends and his assistant Klaus Hinrichsen, a young art historian, a room on the first floor of the camp’s administration building. Ahrends christened the outfit the “Cultural Department”. But Daniel, having learned that his charges included a considerable number of eminent academics, insisted that it be known as “Hutchinson University”.

The Department’s remit was wide-ranging: programming lessons and theatrical performances, arranging the borrowing of books from local and mainland libraries, securing materials for the artists, supplying musical instruments, and organising the teaching of English. As well as the Camp University, the celebrated fashion designer and art school professor Otto Haas-Heye established a school of textiles.

To support his petitions for release, Ludwig Warschauer, a man much disliked by the artists in the camp, who suspected him of being a secret Nazi-sympathiser, founded a technical school to teach younger internees electrical engineering. Despite the enviably rich cultural life, depression was rife as inmates waited for news of their loved ones and worried about their businesses amid the looming threat of Nazi invasion.

“Lest this all sounds too rosy a situation,” Klaus Hinrichsen noted, “let me assure you that all these frantic activities were entered into as a means of distraction from the everpresent anger at the injustice… the constant worry about wives and children left without a provider… from the lack of communication and, of course, suffering from the cramped living conditions and the lack of freedom.”

In the autumn of 1940, the tide of public opinion turned and the realisation that the authorities had arrested thousands of innocent refugees became widespread. A trickle of releases became a flood and, by the summer of 1941, most of the artists and academics had been freed. Other, less eminent individuals were made to wait far longer.

Those who attended the Camp University treasured the memories of those strange, emotionally chaotic months throughout their lives. “I have been to three universities, and this was the best one,” said Fred Uhlman, a lawyer turned artist.

WHILE THE internees had been relatively comfortable, internment was a near-constant misery for most. At least 56 detainees died on the Isle of Man, some to suicide.

Every government must balance its humanitarian obligations with the need to uphold national security. To categorise refugees from Nazi oppression as “enemy aliens”, however, was to invite populist scorn and hatred upon those in most need of compassion. The injustice became clear when thousands of the interned men joined the British Army to fight Hitler after the government allowed former internees to transfer to fighting units in 1942.

Many Hutchinsonians were among 4,000 internees who joined the Pioneer Corps direct from internment camps and participated in the Normandy landings in June 1944. Hutchinson optician Horst Archenhold designed the periscope used to turn Sherman tanks into amphibious craft on D-Day, while Joseph Otto Flatter produced cartoons for Ministry of Defence propaganda leaflets, more than two billion of which were dropped over Germany.

In the decades that followed, many Hutchinson alumni made substantial contributions to British culture, which was shaped in meaningful ways by those artists and thinkers, architects and musicians who had escaped to Britain.

From the Glyndebourne Opera House to the Edinburgh Festival, the contributions of these and hundreds of others continued to pay dividends beyond the frame of their lifetimes. Only a single sentence spoken by Sir John Anderson in the House of Commons on August 22, 1940, months before most of Hutchinson’s internees were freed, provided something approaching an apology: “Regrettable and deplorable things have happened.”

Those in power later acknowledged that the great mistake was treating all refugees as enemy aliens but, unlike in the US where the internment of Japanese citizens during the Second World War has been a subject of ongoing debate and lament, in Britain the subject is rarely acknowledged.

The battle between a nation’s responsibility to help those in need and to maintain national security persists in every age, every generation. In every era, the question remains the same: How far can a democratic society go in the rightful defence of its values before it abandons them along the way? 

Simon Parkin is an author and a contributing writer for the New Yorker. His latest book The Island of Extraordinary Captives (Sceptre, £20) is out now. For free UK P&P, call Express Bookshop on 020 3176 3832 or click here.