The following excerpt is taken from The Clan Leask website ( http://www.clan-leask.org.uk/history/origins-of-the-name-leask) where more information can be found.
In 1341-1346 a Charter of Confirmation of the Leask Lands of Leskgoroune was granted by David II, son of Robert the Bruce, to William Lesk, the first Chief of the Leasks in Aberdeenshire, to replace the earlier lost Charters. The Chapel of Leask dates back to the earliest of times. It is thought that a Colomban Oratory stood on this land about the end of the sixth century. The ruins of the present building, constructed about the thirteenth century, stand on the site of the ancient chapel.
Despite having their own Chapel, it is recorded in the Parish records of the Church at nearby Ellon, that the Leask Chief, his family, and retainers, were regular attenders at St. Marys Church. Thus in 1380 the parish records reveal that William de Laysk, the Elder, Lord of that Ilk, bequeathed ‘one stone of wax from the Lands of Logy, together with twelve pence of silver in order that candles might be burned for ever, for himself and his wives, Alice de Rath and Mariota de Saint Michael, and for the salvation of his sons and daughters, brothers and sisters, on the Sabbath and other feast days, on their tomb’.
Over the years the Lands of Leask steadily expanded beyond the boundaries of Slains Parish, partly by inheritance, partly by exchange of lands, and by purchase. The Estate included the Home Farm, Mains of Leask, Moss Leask, Byreleask, Knapsleask, Nether Leask, Milton of Leask, and Mill of Leask.