He was born in 1510, the son of John Lyon, 6th Lord Glamis, by Janet Douglas, second daughter of George, master of Angus.
[1] Along with his mother, who had married as her second husband Archibald Campbell of Skipnish, Glamis and others were in July 1537 placed on trial on the charge of conspiring to cause the death of James V of Scotland by poison.
Some time later he was released from prison, but on 3 December 1540 his estates were annexed to the crown by act of parliament.
In the following year he held a command in the vanguard of the Scottish army, which, after invading England, retired before inferior numbers.
[1] On the forfeiture of Sir James Kirkcaldy of Grange, Glamis received on 12 September 1548 the barony of Kinghorn, with other lands.