The name is territorial in origin from the old barony of Danzielstoun. The manor took its name from a man named Daniel, who may have been of Norman extraction. The name was gradually softened, through use, to dennistoun.

Sir Hugh Danzielstoun of that Ilk, was one of the barons who submitted to Edward I of England, although his name does not occur on the Ragman Roll of 1296.

His granddaughter, Elizabeth Mure of Rowallan, married Robert II in 1347 and was the mother of Robert III. This gave rise to the proud saying of the Dennistouns that 'Kings come of us, not we of Kings'.

This close royal connection brought extensive holdings to the family, together with the governship of Dumbarton Castle. Robert de Danielstoun was one of the nobles who stood as hostage for the ransom of David II in 1357.

In 1370 he was commissioner for the peace treaty with England. He succeeded his father as sheriff of Lennox and was keeper of Dumbarton Castle. On his death in 1399, his brother, Walter, forcibly took possession of Dumbarton Castle, claiming that it was now the possession of the family, and held it until 1402.

His kinsman, Robert III, offered him the vacant bishopric of St Andrews as compensation for his surrender of the castle. The offer was generous but Walter died before he could take up his new office.

William de Danielstoun was an officer of the royal household, both to Robert III and his son the Duke of Rothesay. His widow, lady Marjory d a royal pension after his death in 1393.

By the 17th century the designation of the principal family had become that of their estate at Colgrain and they became embroiled the conflict between Charles I and Parliament.

John Dennistoun of Colgrain fought for the Royalist cause through out the civil war and joined the ill-fated attempt by the Earl of Glencairn to restore the monarchy in 1653. The royalists were completely defeated, and although Colgrain succeeded in saving his estate from forfeiture, he died of wounds he received in the conflict.

By the middle of the 19th century the family had reached the pinnacle of local aristocratic society.

Dennistoun of Dennistoun commanded the cavalry militia of Dunbartonshire and was Deputy Lord Lieutenant.

Other branches of the family became prominent Glasgow merchants, and John Dennistoun was MP for the city from 1837 to 1847.

From an article in the Scottish History Review...

The Dennistouns of Dennistoun