Being blind in one eye, he was known as "Ian Cam". Having been a zealous supporter of William III, as one of the Principal Secretaries of State, he was created Earl of Tullibardine by patent on 27 July 1696, in his father's lifetime, at the Castle of Atre, in Hainault. He became Secretary of State for Scotland but resigned because of the king remaining suspicious of him.
Queen Anne made him Lord Privy Seal in April 1703, a month before he succeeded to his father's honours. On 30 June 1703 he was created Duke of Atholl. In 1705 he resigned his office of Privy Seal and warmly opposed the Union of Scotland with England. Having joined the Tory party, he was elected a Representative Peer in 1710 and 1713; also Lord High Commissioner to the General Assembly of the Church of Scotland 1712 to 1714.
His eldest son and heir apparent at the time was attainted for high treason in 1715, so he procured an act of Parliament for vesting his honours and estates, after his death, in his next surviving son, James Murray. He also supported the Hanoverians. Lockhart described him as "endowed with good natural parts, though by reason of his proud, imperious, haughty, passionate temper, he was in no ways capable to be the leading man of a party which he aimed at".

Source: Leo van de Pas