The third son of Sir Gerrard Napier, 1st Baronet, of More Crichel in Dorset, by Margaret, daughter and co-heiress of John Colles of Barton St David, Somerset, he matriculated at Oriel College, Oxford, 16 March 1654, as a fellow-commoner.
The House, however, decided that the franchise should be confined to the "select body", i.e. the mayor, aldermen, and burgesses, who had voted for Napier by a majority of 33 to 22.
[2] In France, he kept company with the deposed James II of England and his son, the future Old Pretender.
[2] In 1667 Napier went for three months to Holland with his mother's brother-in-law, Henry Coventry, a diplomat sent to negotiate the Treaty of Breda.
[2] In 1656 Napier's father married him to Blanche, daughter and coheiress of Sir Hugh Wyndham, justice of the Common Pleas and his first wife Jane Wodehouse.
On the death of his grandson, the sixth baronet, in 1765, the estates passed to a cousin, Humphry Sturt, who built up Crichel House there.