The Lockharts
This family is believed to have been the first owners of the Barony of Kilmarnock, but no proof survives. They did own several estates in Ayrshire and Lanarkshire about the year 1160. The two villages known as Symington, one in each district, take their name from Simon Loccard, a Flemish knight who came to Scotland shortly before this date.
Another Loccard, Stephen, held Stevenston in North Ayrshire and by 1205, Riccarton, a suburb of Kilmarnock developed as a separate town, probably taking its name from a Richard Loccard. The family also held Barr Castle in Galston from around 1296.
It was also the Loccards who founded the Church of Kilmarnock, dedicated to St. Mernock, where the town itself gets its name.
It is possible that the first Loccards came to Britain during the Norman Invasion of England in 1066 and in around 1141 came to Scotland as paid soldiers. Many such mercenaries were invited to Scotland by King David 1st, who had been greatly impressed by their organisation which he witnessed growing up in the English court. He gave the Norman knights grants of land for service in order to introduce their Feudal System into Scotland as a pattern of Government.
One such man was Robert de Brus, among whose descendants would be Robert (the Bruce) 1st of Scotland. Another was Walter fitz-Alan whose family was granted lands in Ayrshire and would also become the hereditary Stewards of Scotland (this means they were in charge of the King's money), and would from then on be known as the Stewarts. Eventually the Stewarts gained the throne of both Scotland and England, creating Great Britain. The Loccards were vassals of the powerful Stewarts and Lockhart is still a very common name in this area of Scotland.
In 1330 Sir James Douglas led an army of Scottish knights on a crusade against the Moors in Spain. His friend and King, Robert the Bruce, had always wished to do this, but died before he was able to go, so Douglas carried Bruce's heart in a casket. At the Battle of Thebas, the Scots were surrounded and Douglas threw the casket into the thickest part of the battle and charged, daring his men to follow the Bruce once more. Douglas and most of his men were slaughtered.
One surviving knight, Simon Loccard of Galston, allegedly helped rescue the casket, and bring it back (along with Sir William Keith, also of Galston) to Scotland to be buried in Melrose Abbey, where it lies to this day. The lead casket was recently opened and DNA tested, proving that it did indeed belong to the famous King, before being reburied.