[5][6] Many of the priory's muniments are held in the archives of Eton College, which King Henry VI endowed with the appurtenances when the house was dissolved in about 1440.

[4] By the early 12th century Lonlay was acquiring many endowments, while William de Bellême was in confrontation with Henry I of England both in his English and his French domains.

These incorporate a series of ornately carved capitals directly comparable to examples in Normandy of the last decade of the 11th century, while also showing elements of late Anglo-Saxon style more typical of the English Romanesque.

A famous descendant of William's and Emma's, John de Courcy, made himself virtual Prince of Ulster after conquering it in 1177.

Around 1183–84, he granted to the Priory of St. Andrews in Stogursey "ten carucates of land and all its appurtenances in the Country of Lart or The Ardes", in County Down, Ireland.

Hamilton distinguished the adoption of Blackabbey directly as a cell of Lonlay to the time of de Courcy's successor, Hugh de Lacy: it was, at any rate, referred to as "a certain priory or cell named 'Prioratus S. Andreae en le Arde, in Ultonia'" when, in around 1350, the Priory of St Mary of Lonlay effectively dissolved it and assigned it with all its lands to Richard FitzRalph, Archbishop of Armagh, and his successors.

[14][16] The priory of Stogursey dwindled over the years and was repeatedly taken into the king's hands, at one time let to one of the burgesses, Johannes Bakeler (the town's MP).

[17][18] Today virtually nothing remains of the abbey, apart from the Church of St Andrew itself (a splendid if somewhat over-restored survival, which also serves the village), and the dovecote.