In 1684, he succeeded his father as Earl of Loudoun, Lord Campbell of Loudoun, and Lord Tarrinzean and Mauchline, which gave him a seat in the unicameral Parliament of Scotland as soon as he came of age. While his year of birth is unknown, it can be estimated from the fact that he took his seat on 8 September 1696 and would normally have done so at the age of twenty-one.
