To generations of Irish children his is the rather frightening head that stares out of a glass shrine in St. Peter’s Roman Catholic Church in Drogheda, Co.Louth. Even if you knew what to expect as a child it was a memorable sight – probably the stuff of many a subsequent nightmare.

But before Oliver Plunkett became separated from his head at the behest of elements of the British establishment on 1 July 1681 he had been a distinguished cleric, educated on the continent during the time of the Penal Laws and functioning at a high level in Rome before his appoitment in 1669 to the see of Armagh.

Plunkett had been born in Loughcrew, near Oldcastle in County Meath to weel to do parents of Anglo Norman stock. By the time of his appointment as Primate of Ireland attitudes towards Roman Catholic priests had relaxed sufficiently to allow him to take up his position.

He was a reforming Archbishop. He found Irish priests to be sadly ‘ignorant in moral theology’ – though their lack of such knowledge may have much to do with their inability to acquire a grounding in philosophy while trying to avoid being executed or tarred and feathered at the hands of the authorities in the mid 1600s. The new archbishop also took on drunkenness among members of the clergy, observing that if this habit was squashed Irish priests would become saints. As it turned out he himself was the only Irish cleric of the period to be canonised.

In 1678 Plunkett fell victim to the infamous English Popish Plot of notorious perjurer Titus Oates, who fabricated knowledge of a Catholic conspiracy to murder King Charles II. Oates shopped the Archbishop by alleging that he had evidence of Plunkett colluding to bring 20,000 French soldiers to Ireland. Plinkett might have chosen discretion and headed back to Rome but instead he insisted in remaining in Ireland, though he, sensibly, went on the run. He was captured and tried in Dundalk where numerous informers came forward to confirm the charges against him. The Lord Lieutenant of the day, the Duke of Ormonde, privately referred to them as ‘silly drunken vagabonds whom no schoolboy would trust to rob an orchard.’ The trial quickly collapsed so Plunkett was brought to London to face charges there instead. A grand jury found no case against him but he continued to be detained until the Crown could find witnesses who would stitch him up with the help of a co-operative judge, in this case the Lord Chief Justice Sir Francis Pemberton.

Plunkett was found guilty of ‘promoting the Roman faith’ in June 1681 – which was probably a fair cop, though far from plotting regicide. The penalty, however, was the same in both cases, and on 1 July 1681, the incumbent Roman Catholic Archbishop of Armagh became the last Catholic martyr to die in England when he was hanged, drawn and quartered at Tyburn. In case you are wondering what is involved in the ancient practice of hanging, drawing and quartering, believe me you don’t want to know. His head eventually found its way to Rome, went from there to Armagh before being installed in Drogheda. Most of the his body was interred in Downside Abbey in Somerset. That’s Down –SIDE Abbey, it’s actually the real thing, a monastery, unlike the home of the fictional Crawley family.

Since his death Plunkett’s trial has been described by many distinguished British jurists as an egregious miscarriage of justice, even by 17^th century standards.

Oliver Plunkett, canonised in 1975, was appointed to the see of Armagh, 345 years ago, on this day.