How the Sinclairs became the Lords of Caithness

When we reach Castle Sinclair Girnigoe, the name provides the first clue to the family that built its power there. Sinclair is not originally a Caithness name, nor even a Scottish one. It comes from Normandy, where the family’s ancestors belonged to the aristocratic world of castles, inherited land and loyalty to powerful rulers. Their descendants settled at Rosslyn near Edinburgh and became valuable servants of the Scottish crown, but their journey into the far north came through marriage rather than conquest.

That marriage carried the Sinclairs into Orkney, where they inherited a claim to an earldom still granted under the authority of the Norwegian king. This placed them in an extraordinary position. They possessed land and influence in Scotland while governing within the old Norse maritime world of Orkney. They understood the Scottish court, but they also controlled islands whose connections ran across the Pentland Firth and into Caithness.

William Sinclair knew how to operate within both worlds. He inherited the Orkney earldom, served as Chancellor of Scotland and became one of the country’s great architectural patrons at Rosslyn. The Scottish crown granted him the earldom of Caithness in 1455, but the title did not automatically make his family masters of the county. Authority had to be made visible, enforced and eventually accepted. The Sinclair earls expanded and fortified the castle on the Girnigoe promontory, transforming it into the administrative and political centre of their power in Caithness.

From here, the Sinclairs collected revenue, administered justice, rewarded followers and confronted rivals. Local people approaching the castle might come seeking protection, presenting a dispute or discovering what the earl had decided on their behalf. Through marriage, landholding and successive generations born in the county, the Sinclairs gradually stopped being outsiders and became the dominant family of Caithness. The castle did not appear because they already controlled the county. It helped them to control it. The king supplied the title, but the Sinclairs built their power from stone, law, loyalty and, whenever those proved insufficient, force.

To learn more, book one of our North Coast Explorer private tours.