Following the arrival of the Normans in Ireland in 1169, Henry II, gave a vast tract of land to one of his retainers, Hugh De Lacy. This land stretched from Dublin to the Shannon. De Lacy in turn granted the lands of Castleknock (Cnucha) and the surrounding district by charter to his liegeman, Hugh Tyrrel. His grant of land included what is now called the Pheonix Park, in addition to Clonsilla and Mulhuddart. Tyrrel in 1173 began fortification of Cnucha.
In 1299, an inquisition into the Estate of Hugh Tyrrel, the fifth baron who had died, showed that his Estate at Castleknock was something in the region of 7000 acres. Before the end of the 13th century, various families had settled in the district and their names were well know in the district, Abbot, Balnchard, Keppock, Luttrell, Pilate, (Pellet) and Dueswell (Diswel). The Luttrells were a Norman family who first came to Ireland in 1204. At that time, Geoffrey Luttrell was granted the cattle and manor of Luttrellstown by King John in reward for services.
The name, “Westmanstown” is first mentioned in records in 1821. It is believed to be a corruption of the name “Waspayle”, a Norman family who were recorded in the area in the 16th century. The Kestrel, which can be easily identified on the Westmanstown symbol, is a member of the falcon family. It is readily identified hovering as though suspended for an invisible line. The male is beautifully marked with a blue-grey and white tip, and red-brown upper parts, spotted with black. These birds are evident around the grounds of the club.