The Barony of Eaglesham (1158, Egilsham; 1309, Eglishame)[2][3] formed part of the grant made by David I (1124–53) to Walter fitz Alan, the founder of the house of Stewart.

[8] John de Montgomery and his brother are listed on the Ragman Roll, rendering homage to Edward I of England for their estates in 1296.

[10] Ransoming important captives was the custom in the 14th century and Sir John used the money paid over by the English for the release of Hotspur to build himself a fine castle at Polnoon.

[13] The ballad of the 'Battle of Otterburne' commemorates the events of 1388 that led to these developments: The Percy and Montgomerie met, Of other they were richt fain, They swakked swords until they swat, And their red blude ran between.

[19] In the fourteenth century the baronies of Eglinton and Ardrossan were obtained by the marriage in 1368[20] of John de Montgomery with Elizabeth, daughter and heiress of Sir Hugh Eglinton, by a half-sister (Robert and Egidia share the same father, but have different mothers), Egidia, of Robert II, King of Scotland.

[26] Timothy Pont's map as published by Johan Blaeu in 1654 illustrates Polnoon as a central single-storey house with a flanking building on each side, joined to the centre by a fence-like structure.

[27] The motte lies about a mile south of Eaglesham church, sitting on a promontory with views of the surrounding countryside.

Today (2009) large chunks of masonry appear almost randomly scattered across the site and in the Polnoon Water; very little remains in place as recognisable structures.

On the west side, the ground falls steeply to the Polnoon Water, which forms a confluence with the White Cart nearby.

[13] It is related that Sir John Montgomery caused a spur (Hotspur) to be carved and placed above the door of the castle in memory of his exploits with Henry, Lord Percy.

The armorial panel does not date from the marriage between the Montgomery and Eglinton families as shown by Sir John's seal which did not bear his wife's quartered arms; the only inclusion of the Eglinton family at this time was an annulet placed in the centre of the Montgomery shield bearing the fleur-de-lis.

[32] In heraldic terms the full Montgomerie arms are described : Quarterly, 1st & 4th grand quarters, counterquartered, Azure three fleurs-de-lis Or (Montgomerie); & three annulets Or, stoned Azure (Eglinton); all within a bordure Or charged with a double tressureflory counterflory Gules;2nd & 3rd grand quarters, counterquartered, Or, three crescents within a double tressure flory counterflory Gules (Seton); Azure, three garbs Or (Buchan), overall an escutcheon parted per pale Gules and Azure, the dexter charged with a sword in pale Proper, pommelled and hilted Or, supporting an imperial crown, the sinister charged with star of twelve points Argent, all within a double tressure flory counterflory Gold.

[13] On 19 April 1586, Hugh, 4th earl, is said to have set out from Polnoon on a journey to Stirling, and whilst crossing the bridge over the Annick Water he was attacked by the lairds of Robertland, Aiket, some other members of the Cunninghame clan and shot dead.

[37] Polnoon Castle was refurbished for occupation in 1617,[38] but was a ruin by 1676 and rapidly fell into decay, no doubt being robbed for building materials when the earl's new village of Eaglesham was being built in the 18th century, circa 1769.

The Earl's kennels for his hunting dogs were located on a site at what is now Lynn Cottage within the Orry in an area still known as the Gamekeeper's Park.

Feudal justice may have been dispensed on this 'Justice or Court Hill' and another knoll nearby named Gallowshill was where execution of the 'doom' or sentence would have taken place.