The original letter written by the informer who betrayed Michael Collins to the British is to be auctioned in Dublin next month. His letter was intercepted by an IRA spy in Dublin Castle.

The historic document could fetch over $4,000 according to Adams auctioneers, charged with handling the sale after the letter came to light recently.

The Irish Times reports that the document, although known to historians, has never been published in full.

Dated November 11th, 1919, the letter was signed by ‘H Quinlisk,’ a former corporal in the Royal Irish Regiment, from 21 Gardiner Place, Dublin and was sent to the Under Secretary at Dublin Castle.

Quinlisk wrote: “I was the man who assisted Casement in Germany, and in coming home I have been connected with Sinn Féin.

“I have decided to tell all I know of that organisation and my information would be of use to the authorities. The scoundrel Michael Collins has treated me scurvily.”

At the time of the letter, the Irish War of Independence was already under way.

The British authorities had placed a £10,000 reward on Collin’s head, making him the most wanted man in the British Empire.

The Co Wexford-born son of an RIC constable, Harry Quinlisk joined Roger Casement’s Irish Brigade while a prisoner of war in Germany.

The report adds that his betrayal was apparently prompted by Collins’s refusal to bankroll his gambling habit.

The paper adds that his letter to the British authorities was intercepted by Collins’s spy inside Dublin Castle and the IRA set a trap for Quinlisk.

It says that he was picked up by IRA volunteers at Ballyphehane and his body, riddled with seven bullets, was later found in a field.

Buttons said to be on Michael Collins when he died have been auctionedGoogle Images