Sempill was born at
Castle Semple, Scotland, the son of Hon. Archibald Sempill of Dykehead and the grandson of Hugh Sempill, 5th
Lord Sempill. Being a
Roman Catholic, he was sent to be educated in France and by 1688 was an
ensign in the French royal
Scottish Guards. In 1708 he became a captain in the Regiment of Galmoy before transferring to the Regiment of Dillon in the
Irish Brigade in 1715. On 11 May 1712, Sempill was the subject of a "declaration of nobility" by the exiled
James Francis Edward Stuart, which recognised Semphill as the legitimate heir of his Lord Semphill ancestors and thereby created him
Lord Sempill of Dykehead in the
Jacobite peerage. This was despite the title in the
Peerage of Scotland remaining extant with Francis Sempill, 10th Lord Sempill as the holder. He married Elizabeth Abercromby and they had four children. He was succeeded by his eldest son,
Francis Sempill, who became a leading Jacobite agent in Paris. ==References==