The Royal Society of Chemistry last week discovered, during work on its archives, a previously unknown account of a woman who joined the organisation after exposing a First World War German spy ring operating in England.
The emerging story of modest Mabel Elliott also reveals how - after she became suspicious of an envelope and its letter while working as a censor - chemists detected messages, potentially disastrous for Britain, written in lemon juice.
On Armistice Day this week the RSC will feature the spy drama on its website, following the unearthing of the story in its Piccadilly library.
Although her vigilance may have prevented an invasion by the Kaiser, she was never recognised for the coup in her own lifetime, because she gave evidence under the false name Maud Phillips in the trial held at the Tower of London.
Professor Lesley Yellowlees, who will become the first woman President of the RSC in July, said today:
"Mabel Elliott demonstrated astounding energy and dedication throughout her career; now that we have these facts about the spy plot we should recall her with great respect. Also, we can be proud of the fact that chemists literally read between the lines to detect hidden messages.
"I cannot help but speculate about the avenues that would have been opened to Miss Elliott in today's world, where women's talents and commitment generate, on the whole, better rewards."
Mabel Elliott, who joined the RSC as an indexer and manager following the Great War, had previously been deputy assistant censor at the War Office and it was there, in 1915, that she became suspicious of an envelope containing, ostensibly, a business letter.
Invisible words in the letter had been added by a German spy, Anton Kuepferle, a naturalised American, and the secret messages concerned dispositions of Royal Navy ships around the coast, as well as deployment of forces defending London.
The discovery by Miss Elliott, noted for her attention to detail, led to Kuepferle's arrest and subsequent trial. However, before the trial could conclude, he hanged himself in Brixton gaol, fearing the scaffold, and confessing, by scrawling on a slate, his true identity as German army officer. His two accomplices, Hahn and Mueller, were also later tried and convicted.
Miss Elliott had become suspicious of the envelope, addressed to a "friend" in Holland by the 27-year-old spy, who had arrived in Liverpool having, previously lived in New York City.
When she retired from the Royal Society of Chemistry in 1937, seven years before her death at 59, the society conferred upon her an Honorary Membership, making her the first woman to receive the honour.
Even during the Second World War her energies were applied to the national good, as an interpreter to Belgian, French and Dutch refugees after Dunkirk, and escorting trains loads of women en route to an internment camp.
She then passed Red Cross examinations, so that she could give all her spare time to nursing, before becoming Commandant of the 78th Middlesex Detachment.
During the blitz she tended elderly people in London, returning home night after night, sheltering in doorways from falling shell splinters.
Mabel Elliott underwent some of her education at a German convent school in Holland, becoming fluent in German and Dutch; she then studied in Brussels, becoming proficient in French. Back in England she took a course in business training at Pitman's College where she was awarded the prize for French and German.
She also won the All-England gold medal for shorthand speed and typing in foreign languages.
In an RSC journal The Analyst, a 1944 obituary on Miss Elliott commented:
"She would not let herself be cast down by troubles that would have made many despond. Even when it came to the last great trial, she faced an operation and a painful lingering illness, which she knew would probably prove fatal, with the same unflinching spirit that she had shown towards the German blitz.
"A favourite quotation of hers was Hugh Walpole's 'It isn't life that matters! It's the courage we bring to it.'"
Mabel Elliott obit Analyst 1944