In 1950, in the course of rebuilding works on an old house in Summerhill in Co Meath, this remarkable stone was found behind a blocked doorway. It had been in a window recess of a secret sealed-up chamber. It is a rough piece of sandstone.

On its face is a carving of the Crucifixion along with the symbols of Christ’s Passion and the date 1740. The imagery is vernacular and earthy: the rope used to tie Jesus’s hands, the cock that crowed to mark his betrayals by Judas and Peter, the dice thrown by the Roman soldiers, the hammer and pincers used in the Crucifixion, and the temple of Jerusalem. The shape of the cross suggests it was based on those sold to pilgrims at Lough Derg.

The stone was clearly used for secret Catholic worship. As such it speaks both to the severity of attempts to repress Catholicism and to their failure.

Irish Jacobite resistance, and the hopes for a reversal of the huge transfer of lands from Catholic to Protestant owners, ended with the Treaty of Limerick in 1691. But the treaty did seem to secure the existing property and religious rights of the defeated Catholics. It promised that Catholics could have the same level of tolerance “as they did enjoy in the reign of King Charles the second: and their majesties, as soon as their affairs will permit them to summon a parliament in this kingdom, will endeavour to procure the said Roman Catholics such farther security in that particular, as may preserve them from any disturbance upon the account of their said religion”. Those Catholic members of the landed gentry who swore allegiance to the new regime could keep their lands.

These promises were not kept. Instead, a series of penal laws against Catholics was put in place. The Protestant ascendancy did not regard itself as secure: France remained a threat, as did the papacy’s continuing support for the Stuart cause. Some former Jacobites remained active as “rapparee” or “tory” outlaws. In 1695, the promised parliament in Dublin passed laws that prohibited Catholics from bearing arms, owning militarily useful horses or travelling to the Continent to be educated.

Gradually, these concerns with security turned into a more nakedly religious project of penalising Catholicism itself. Laws “for the suppression of Popery” passed in the early 18th century required bishops, deans, vicars general and friars to leave the country and remaining clergy to register with the authorities; excluded Catholics from parliament, corporations, the army and navy, the legal profession and civic offices; and prevented Catholics from buying land, leasing it for more than 31 years or running schools.

The penal laws helped to underpin Protestant domination of landholding.

The Catholic share of the land continued to fall, from 14 per cent in 1702 to 5 per cent by 1776 (though many landowning families were converts or crypto-Catholics).

But in general the laws were an obvious failure. The large majority of the population remained Catholic, and sporadic persecution failed to stop the production of Irish priests by continental seminaries.

Catholic worship continued, albeit, as the Crucifixion stone shows, often in secret. The penal laws were evaded, flouted or, if necessary, endured.

They did not “suppress Popery”.

Where to see it National Museum of Ireland – Decorative Arts History, Collins Barracks, Benburb Street, Dublin 7, 01-6777444, museum.ie