James Cornwalsh

In 1358, Sir John petitioned the Crown for redress, on the ground that his castle of Kylebelle (now vanished, it is thought to have been near Leighlinbridge), had been burned by the Irish of Leinster.

[8] In 1434, he was placed on a high-powered judicial commission, whose members included his fellow Chief Justice, John Blakeney of the Common Pleas and his junior Baron, Reginald de Snyterby, to inquire into all suspected cases of treason in Dublin and the Pale.

[10] The same judges had sat on previous commissions, notably in 1426/7, when they tried a charge of felony against the Bishop of Meath, Edward Dantsey, who was accused of stealing a chalice from a Church in "Taveragh" (probably Tara).

Perrers was an English-born military commander and an influential statesman, who acted as Deputy to the Lord Lieutenant of Ireland, and was a close associate of James Butler, 3rd Earl of Ormond.

The Fitzwilliam family, for centuries, were the principal landowners in Dundrum and adjoining parts of Dublin, and constantly sought to expand their holdings.

On 28 September 1441, when Cornwalsh had come up to Baggotrath to hold the Michaelmas assizes Fitzwilliam, according to the subsequent charges, assembled a large military force, seized the castle and murdered the Chief Baron, who was at supper with some members of his household, seemingly unaware of any danger.

[13] Given the gravity of the crime and the social prominence of the victim, it is surprising that Fitzwilliam and Ismaye were soon pardoned for killing Cornwalsh, and were even allowed to retain possession of Baggotrath Castle in the short term.

[13] It was in any case quite easy to get a royal pardon from Henry VI, even for crimes as notorious as the 1455 murder of the Devonshire lawyer Nicholas Radford by Thomas Courtenay, 6th Earl of Devon, which gravely shocked English public opinion.

On the other hand, given the number of equally heinous crimes in England, such as the Radford killing, it is perhaps fairer to conclude that there was a serious breakdown of law and order in both kingdoms, which greatly weakened the authority of the Crown.

An inquisition of 1448 found that Ismaye was not the heiress to the Perrers estate, which should rightfully pass to the next male heir, John Hall of Southwark.