From: a book on Scottish Surnames
LYON – Originally de Leonne. The family came into England with the Conqueror. Sir Roger de Lyon settled in Scotland in 1089, where he received a grant of lands in Perthshire, which he named Glen Lyon. Afterwards John de Lyon obtained from David II a grant of the baronies of Forteviot and Fergundeny in Perthshire and Drumgawan in Aberdeenshire; His son, Sir John Lyon, was secretary to Robert II, whose youngest daughter, Lady Jane Stewart, he married, and was created Lord Glamis, made Great Chamberlain, and Lord Chancellor of Scotland, and received grants of the Thanedom of Glamis in Forfarshire, and of the Barony of Kinghorn in Fifeshire, and was authorized to surround his arms with a double tressure in honor of his alliance with the royal family.