A ramshackle bicycle clunked along the rough roads of Criel, France. With each pot hole, the rider was jolted forward unceremoniously, holding a felt hat tightly to her head under the glare of the summer sun - she was just 15 miles from the front line.

In her own words, she was a picture of unloveliness. And her prim, middle-class attitudes and dress had been left on the other side of the English Channel.

As Dorothy approached a cafe, where she would set up base for a brief period, the crack of machine-gun fire could be heard across the fields. Her arrival was greeted with bewildered stares from the locals - what was la petite anglaise doing here? Was she a nurse? Or a visitor?

No, it was the summer of 1915, and Dorothy Lawrence was intent on joining the British troops. Two months later she would become the only woman soldier to experience front-line fighting in the Great War. Her incredible story was dismissed for more than 80 years as a folk tale, until Richard Bennett, the grandson of Richard Samson Bennett, one of Dorothy's accomplices in the adventure, uncovered her autobiography while researching his family history at the Royal Engineers' Museum.

Titled Sapper Dorothy Lawrence, this stirring tale of bravery and danger was not fully appreciated until Raphael Stipic, a historian from East Sussex, stumbled across a letter written by Walter Kirke, head of the secret service for British Expeditionary Force, during the First World War.

Kirke spoke of a Miss 'Young' who donned men's clothing and headed for the front line in the hope of becoming a war correspondent. Kirke's details pointed unequivocally towards Dorothy Lawrence. Her story is now part of an exhibition at the Imperial War Museum on women at war.

She is believed to have been born out of wedlock in Hendon in the 1880s, and was adopted by a guardian of the Church of England. She returned to the area towards the end of her life when she was incarcerated at Friern Barnet Mental Asylum in Colney Hatch Lane. Finally, she was buried in a pauper's grave at New Southgate Cemetery.

Back in 1914, Dorothy was a budding journalist in a male-dominated industry. Universal suffrage was still a dream, but Dorothy, then in her mid-twenties, was determined that not having a vote would not stop her rise as a journalist.

She achieved some success with a few articles published in The Times before the start of the war, but her determination to take her notepad to the front line was met with scorn by male peers.

Numerous attempts to join the Voluntary Aid Department, which sent women to participate in war work, were rejected, so she resorted to guile and subterfuge to achieve her goal.

Leaving with her rickety bicycle, a brown bag and rudimentary French, she boarded a ferry at Folkestone heading to Boulogne, in the hope of reaching the front line disguised as a man.

Despite the expanses of rubble and the rumble of falling shells, Dorothy found the French clinging on to their famous joie de vivre. Passing through Paris she headed towards the war zone, picking up some shooting lessons along the way thanks to amenable French soldiers.

But her journey was halted when she was arrested by French police in Senlis, two miles short of the front line. She was ordered to leave the area and fled to a forest. where rats, squirrels and 'invisible beasties' troubled her. In the depth of night she felt like her blood was freezing. Despite the certainty that she would be plagued by insect bites, she made her bed in a haystack for the night. Her luck changed at the encounter of two British soldiers in a Parisian cafe, who would come to be known as her khaki accomplices.

After receiving a smuggled uniform from the kind soldiers, known as her 'Khaki Accomplices', Dorothy adapted the clothes to conceal her feminine figure, and used bandages to hold down her bosom.

At the train station, a freckled Scot shaved her hair and ran a razor across her smooth cheeks in the hope that stubble might make her disguise more credible.

In Albert, just behind the front, a Royal Engineer, or 'sapper', named Tommy Dunn agreed to hide Dorothy in a cottage until she could slip into an army tunnelling company. The plan worked and she was soon involved in digging under enemy lines and placing bombs to bring down enemy trenches.

With Germans raining mortar fire down on her, Dorothy would tunnel her way with a 'mate' towards their lines, but despite her fighting words and brave actions, she could not bring herself to light the fuse on a bomb.

Worse was to come. Freezing weather, incessant fire and a lack of food led Dorothy to suffer fainting after ten days in the trenches. Fearing she would be discovered if she was taken ill, she decided to admit all.

A suspicious judge, fearing she could release sensitive intelligence, ordered that she remain in France until after the Battle of Loos. Dorothy was forbidden from selling her story to a newspaper. When she finally put pen to paper, her story was censored by the Ministry of Defence.

In 1919, she moved to Canonbury, Islington, but after claiming she had been raped by her church guardian, she was institutionalised in 1925. She died in Friern Barnet Hospital in 1964.

Mr Stipic said: "I just couldn't believe that it was true at first. I want to piece together more of her life and write a book."

Anyone with information about Dorothy can write to Mr Stipic at 11 Risbridge Drive, Kedington, Suffolk CB9 7ZE, or call on 07734 096328. They can also email the address below.