Accompanied by a female French agent, they investigated casual talk by Allied soldiers about troop movements.

For the next five years, he became a staff lecturer at the Ministry of Information and wrote patriotic British novels like Siegfried Spy and Death to the Fifth Column.

The theme of the book, to bring peace to the world, centred around an invasion of the UK, the US and Russia by aliens.

Newman lied about his age to enlist at 17 and clarified in his 1960 autobiography, Speaking From Memory, that his war service was routine and unremarkable and that his novels were publicised in that way to achieve sales at the suggestion of his publisher, Gollancz.

Correspondence between Newman and the military historian B. H. Liddell Hart held in the Liddell Hart Centre for Military Archives at King's College London, confirm Gollancz's marketing tactics by asking Newman to 'disappear' for two weeks during the book's initial presentation to the public.

I quite agree that there are plenty of people who might believe it, but I believe the intelligent reader will treat the book exactly as he would a good detective story.That statement was widely reported in the press worldwide, but even his 1968 New York Times obituary repeated the fiction.

He had noticed large concrete structures, and spoke with local villagers who reported noises resembling an express train.

This information pre-dates the Oslo Report by a full year, and led to extensive research by Newman.

It resulted in a radio script for the BBC program Now it can be told, a novel on the Polish resistance contribution to the war effort They Saved London, and the subsequent film Battle of the V-1.

In a reverse compliment and recognition of Newman's work, Poland have named two memorials to the Polish Resistance as "They Saved London".

It is not suggested that Newman was ever employed as a spy, but that he was an enthusiastic amateur who regularly reported back to the British government in London after his travels.