Denis Sefton Delmer, known familiarly as "Tom", was born in Berlin as a British subject, as a son of Australian parents living in Germany.

His father, Frederick Sefton Delmer, was British of Australian heritage, born in Hobart, Tasmania, who became Professor of English Literature at Berlin University and author of a standard textbook for German schools.

[2] Delmer was educated at the Friedrichswerdersches Gymnasium [de], Berlin, St Paul's School, London, and Lincoln College, Oxford, where he obtained a second-class degree in modern languages.

He was "embedded with Nazi party activists" at this time, "taking copious notes on everything from the style of the would-be Führer's oratory to the group think that lay behind the bond he was forming with the German people.

[7] Delmer covered important events in Europe including the Spanish Civil War (reporting with Ernest Hemingway, Martha Gellhorn and Herbert Matthews[8][9]) and the invasion of Poland by the Wehrmacht in 1939.

[13][14][15] Delmer considered that British wartime attempts to counter German propaganda were misguided, with broadcasts aimed at anti-Nazis who did not need convincing, in what today we call an echo chamber of like-minded people.

The station name, "Gustav Siegfried Eins" (phonetic alphabet for "GS1") left a question in listeners' minds – did it mean Geheimsender 1: (Secret Transmitter 1) or Generalstab 1 (General Staff 1)?

Peter Seckelmann [de], a former German writer of detective stories who had fled Nazi Germany, was recruited from a Pioneer Corps bomb-disposal squad in London and he was the first member of the team to arrive at the discreet house known as "The Rookery" in Aspley Guise.

Owing to an error by a non-German-speaking transmitter engineer, the programme was accidentally repeated and "Der Chef's" dramatic on-air murder was broadcast twice.

Based in Milton Bryan and connected by high-quality telephone lines for transmission from the Aspidistra transmitter at Crowborough,[32] Soldatensender Calais produced live broadcasts, a combination of popular music, "cover" support of the war, and "dirt" – items inserted to demoralise German forces.

Delmer's black propaganda sought to propagate rumours that German soldiers' wives were sleeping with the many foreign workers in Germany at the time.

[16] Delmer also oversaw the production of a daily "grey" German-language newspaper titled Nachrichten für die Truppe ("News for the Troops"), which first appeared in May 1944, much of its text being based on the Soldatensender Calais broadcasts.

Nachrichten für die Truppe was written by a team provided to Delmer by SHAEF, and disseminated over Germany, Belgium and France each morning by the Special Leaflet Squadron of the US Eighth Air Force.

Reinhard Gehlen stated it was Delmer's Daily Express article of 17 March 1952 which dragged the German intelligence chief into the daylight by unleashing a "flood of further publications".

[2] Delmer wrote two volumes of autobiography, Trail Sinister (1961) and Black Boomerang (1962), and several other books, including Weimar Germany (1972) and The Counterfeit Spy (1971), an account of the Double-Cross deception.

[41] David Hare based his play Licking Hitler on Black Boomerang, and his plot included the faked, on-air discovery and shooting of the broadcaster, in the same way as Delmer had finished the career of "Der Chef".