Seagate Castle

Irvine first appears in the record in 1163, its harbour then by the sea-gait, or Seagate, with a castle built to protect it. Benedict of Peterborough recorded a castle of 'Hirun' in 1184, taken to refer to Irvine, so the original tower or motte, probably wooden, stood before that date; it was rebuilt in stone in the 1360s. King Robert II made Irvine a royal burgh in 1372. Early writers recorded progressive silting, blown sand stranding ships for months at a time; by 1606 the anchorage at Seagatefoot was useless and abandoned.

In the twelfth century the castle lay within the lordship of Cunninghame, granted by David I to Hugh de Morville, Lord High Constable of Scotland. It passed out of de Morville hands in 1196 for want of male heirs and descended through several families, the Balliols among them, until Robert the Bruce granted it to Robert the Steward. In 1366 the Steward, later Robert II, gave the castle to Sir Hugh de Eglintoun with the offices of chamberlain of Irvine and bailie of Cuninghame. Sir Hugh had married the Steward's half-sister Egidia; their only child Elizabeth, sole heiress, married John Montgomerie of Eaglesham, carrying the estates and the barony of Ardrossan to the Montgomeries.

A constable held the castle for the lord: the Irvine muniments name Thomas de Vauce between 1391 and 1425, John de Brakanrig from 1428, and Thomas Spark, who in 1438 sold both lands and office to William Cunningham of Craigends. The two merks paid annually with the post ceased with its demise in 1596.

In 1297 Edward I sent Sir Henry Percy to Irvine with a punitive expedition to quash an uprising against his dethronement of John Balliol. Robert Bruce, Earl of Carrick, Bishop Wishart and others led the Scottish army, camped at Knadgerhill in sight of the English at Tarryholme, the old Trindlemoss loch between them. After much argument the Scots decided to submit without a fight, and Rodolph de Eglinton is said to have hosted the negotiations in the castle then standing on the site. The plaque at the entrance records the Treaty of Irvine as signed at Seagate on 9 July 1297; the original, also called the Capitulation of Irvine, is held in the Public Record Office. Bruce never accepted the surrender conditions and Edward I did not confirm the treaty.

Hugh Montgomerie, 3rd Earl of Eglinton, married Agnes Drummond in 1562, the year his earlier marriage to Lady Jean Hamilton, a daughter of the Earl of Arran, ended in divorce. He remodelled and expanded Seagate around 1565; the showpiece raised between 1562 and 1585 kept the character of a castle or fortalice while running closer in style to a palace or mansion house. His arms sit on a roof boss in the entrance pend with the initials 'HM', beside his wife's arms and 'AD'. The family may have built it both as their town house and as a jointure house for the dowager countesses.

The entrance plaque records that Mary, Queen of Scots stayed at the castle in 1563; the 3rd Earl, a great supporter, is said to have entertained her and her four Marys here. That visit is claimed as the origin of Irvine's Marymass celebrations, though the likelier source is the dedication of the town's church to the Blessed Virgin Mary. The earl died in 1585.

Seagate was inhabited until about 1746, when Alexander Montgomerie, 10th Earl of Eglinton, removed its roof and used the material in a new church he was building in Ardrossan parish. Pococke, travelling in Scotland in 1760, found it ruinous. It became the haunt of smugglers, thieves and beggars, the first place searched whenever property was stolen in the town; people still living in the 1800s remembered the smugglers' 'wee still' in the large kitchen fireplace.

Locals quarried the building for their own purposes. In 1810 Hugh, the 12th Earl, made extensive repairs and blocked up the windows and doors. A great storm in 1839 brought considerable stone down into the courtyard, and an 1883 inspection found the vaults and kitchen full of rubble and refuse, which the Earl of Eglinton had cleared and buried in the Low Green. Mrs Walker of Castlepark gave it to the Burgh of Irvine in 1945.

A trial excavation in October 1992, funded by Irvine Development Corporation, sought the medieval castle and reached deposits 2.8m deep and a short length of wall, without clear dating evidence. The roofless ruin was found in danger of partial collapse in 2010, and North Ayrshire Council carried out consolidation works in 2011. The remains have been a scheduled monument since 1955.