Joe O'Hara is the charming, cocky American radio journalist who turns up at The Halcyon in 1940 and doesn't leave. His boss thinks Britain is a lost cause, but O'Hara sees the bravery around him and wants to tell the story of wartime London. His persistence pays off as his broadcasts pick up a huge following back home.
If you don't recognise the name, don't worry: there wasn't a famous war correspondent called Joe O'Hara. There was, however, a man called Edward R Murrow.
“Edward R. Murrow was someone who came over to Britain to report on the war and was integral to America later coming into the war," actor Matt Ryan explains. "So I spent time just looking at him, his life and what kind of person he was.
"That’s not to say Joe is based on him. There are certainly bits of him that I can pull out and use, just for myself more than anything, because Joe is very much his own person."
But there is a certain similarity between the fictional reporter and the real one – and it goes beyond a physical resemblance.
Who was Edward R Murrow?
American journalist Ed Murrow made his name with a series of radio broadcasts for CBS during World War II, gaining an audience of millions in the US.
Born in North Carolina in 1908 and raised in Washington, Murrow was from a poor background but excelled in school and at Washington State College. By 1930 he had graduated, going on to the Institute of International Education and working for the Emergency Committee in Aid of Displaced Foreign Scholars.
Unlike Joe O'Hara, he was a married man: he tied the knot with Janet Huntington Brewster, who also went on to be a radio broadcaster and relief worker in wartime London. Despite this, he later had an affair with Winston Churchill's daughter-in-law Pamela.
Becoming a war reporter
Murrow signed up with American network CBS in 1935, as director of talks and education. He went to London in 1937 to become the director of CBS's European operations – a role that didn't actually involve on-air reporting. Instead, his job was to persuade European figures to speak on air.
But Murrow was ambitious, and he soon appointed journalist William L Shirer on the continent – creating the nucleus of what later became the "Murrow Boys" team of war reporters.
Shirer was on the scene when Nazi Germany annexed Austria in the 1938 Anschluss. Although unable to get a report out in Austria, he was flown to London to deliver his eyewitness account on the radio. Murrow flew to Vienna and coordinated a team of correspondents from around Europe to give their accounts.
Murrow soon picked up a loyal following in his home country, covering the crises in Sudetenland and Czechoslovakia. The journalist remained based in London when war hit in September 1939, while Shirer reported from Berlin.
War breaks out over the skies of London
Murrow is best remembered for his innovative live radio broadcasts during the Blitz, in London After Dark - a series approved by Winston Churchill, who was desperate to end America's policy of isolationism and get the US public on-side.
Previously, war coverage had come via newspaper reports and newsreels and wire service reports read out on the air. But with Murrow's Blitz reporting, you could hear the sirens wailing and the bombs dropping. The war seemed more immediate and real to that remote American audience.
These reports began with a signature opening: "
This is London." His other catchphrase was borrowed from Londoners, and from Princess Elizabeth's own radio broadcast: "Good night, and good luck".
“We are told today that the Germans believe Londoners, after a while, will rise up and demand a new government, one that will make peace with Germany,” Murrow said in one broadcast. “It’s more probable that they will rise up and murder a few German pilots who come down by parachute.”
Return to America
Murrow headed back to the US in 1941, to a dinner in his honour with 1,100 guests. Franklin D Roosevelt even sent him a telegram.
Pearl Harbour happened less than a week after, bringing America finally into World War II.
More war reporting
As America threw itself into war, Murrow put together a team of journalists (Murrow's Boys) who covered the conflict for CBS from all around Europe.
His efforts were appreciated back in Britain. In 1943, Churchill even offered to make him joint director-general of the BBC - a job he declined.
Instead, he made sure to stay in the field, and in 1945 (alongside Bill Shadel) he was the first reporter at the Buchenwald concentration camp in Germany. What he saw left him lost for words.
Murrow's final broadcast from London was in 1946, before he returned home to become head of CBS News where he continued his career as a newscaster and later moved into television.
Aside from his war reporting, he is also remembered by many Americans for his criticism of McCarthyism and the Red Scare, with a broadcast ("A Report on Senator Joseph McCarthy") credited with helping bring down the senator and his movement.
The Halcyon airs on Mondays at 9pm on ITV