A First World War postcard showing Women's Army Auxiliary Corps members at work.

An appeal has been launched to track down relatives of a Donegal woman who was a member of the first ever military code breaker teams.

While the Second World War's Bletchley Park codebreakers were made famous through films such as “The Imitation Game” and “Enigma,” the skills were first developed in World War One.

Code breakers were used to intercept and de-code messages sent between units of the German army. In the Second World War, their role was seen as decisive in the Allies winning the Battle of the Atlantic.

It has now emerged that a Donegal woman was among the first six de-coders recruited to intercept and translate German messages during World War One.

Catherine Hayes Osborne from Milford worked as a member of the British Woman's Army Auxiliary Corps (WAAC) during The Great War.

According to the Donegal County Museum, she was attached to the intelligence branch of the British army's general staff and worked in the censor's office, decoding German wireless messages.

Spokeswoman, Caroline Carr said: “She became a ‘Hush WAAC,' a nickname given to the dozen servicewomen at St Omer, France, who decoded German wireless messages during the First World War.”

While little is known about Hayes Osborne's life, it is known that she was the youngest daughter of Dr John Allen Osborne and Catherine Hay who were married on March 17 at Ballymacarrett Presbyterian Church in Belfast by the Rev John Meneely. Catherine Hay was the youngest daughter of Thomas Hay from Milford in County Donegal.

Her father was doctor for the Milford Poor Law which included the town's Workhouse. It is also known that her sister, Jane was a general housekeeper with the Voluntary Aid Detachment at Sheffield's Great Northern General Hospital from 1916 until 1918. A brother, John Allan Osborne subsequently became a country solicitor in Milford.

Catherine Hayes Osborne arrived at St Omer in France on September 28 1917.

Ms Carr said: “These women were highly educated and they would have been excellent linguists.”

Many of the German radio messages were routine. However, some gave crucial information about troop movements and other matters.

“The work was secret, hence the nick name ‘Hush WAAC.' Her rank was Assistant Administrator (Second Lieutenant). She wore the same bracers as instructors and a First Army Patch. Unfortunately her service records were lost during bombings in World War Two.”

Ms Carr said Donegal County Museum, along with the Royal Signals museum, was keen to speak to any relatives of the Milford woman. She appealed to anyone with photographs or memories of Catherine Hayes Osborne to contact her at the museum in Letterkenny at 00 353 74 9124613 or by email at museum@donegalcoco.ie.