Exactly 100 years ago today, Eamon de Valera, future taoiseach and future president of Ireland, escaped from Lincoln Gaol in one of the most audacious events of that turbulent period in Irish history.

The event leading up to the daring prison break began in May 1918, when many leading Sinn Feiners were arrested in the so-called 'German Plot' and transported to England to be detained as political prisoners at HM's pleasure. Dev, the Sinn Fein president, was locked up in the imposing fortress of Lincoln Gaol.

As the Great War was ending, an escape was planned. Freeing Dev would not only be an extraordinary coup, but it would serve as excellent propaganda for Sinn Fein.

It has long been held that the escape key was made from an image embossed in melted candle wax. But not so. De Valera's fellow prisoner, Sean Milroy, was an illustrator, contributing to many republican publications. He made a 1918 Christmas card depicting an inmate trying to fit a large key into a small keyhole and a second drawing showing him looking at a large keyhole, captioned 'Xmas 1917, can't get in' and 'Xmas 1918, can't get out'.

The card contained the full specification of the master key. This writer is aware that during a jail visit, Milroy gave his sister, a nun, the card to post or deliver. Letters reportedly followed - written in Irish and Latin to ensure the message was understood.

According to Tim Pat Coogan in De Valera: Long Fellow, Long Shadow, as many as four cakes containing incorrect keys were sent from Ireland in the latter months of 1918, until Kathleen Talty delivered the final key in a cake.

It is probable that the final key was forged in England. Michael Collins, who organised the escape from Ireland, was then the de facto leader of the IRB, which had a strong presence amongst the Irish diaspora in northern England.

With safe houses in place, Collins and Harry Boland cut the barbed wire fencing around the prison on February 3 and gave the signal. Milroy, de Valera and Sean McGarry made their way through a series of doors, unlocking then locking them behind them.

A report in The Anglo-Celt the following weekend stated: "Messrs de Valera, Sean Milroy and Sean McGarry made their escape from Lincoln Prison between 4.30 and 9.30 on Monday evening, and so far their whereabouts have not been discovered. It is thought that they have made their way via Grimsby to the Continent - whether they scaled the 18ft wall or secured a key for the outer gate is still shrouded in mystery."

All were met by Paddy O'Donoghue from Manchester and taken to Worksop, where Fintan Murphy had a taxi waiting to bring the escapees to Sheffield and Manchester.

Collins and Boland made their way to London. Dev stayed with a Fr Charles O'Mahony in Sheffield - and a week later, wearing the uniform of a colonial soldier, he walked arm-in-arm with Kathleen Talty for seven miles to a second safe house.

On February 19, de Valera was smuggled on board The Cambria in Liverpool to sail to Dublin, arriving in the early hours of February 20. The great escape was complete.

Sunday Independent