Nicholas Bagenal was born in
Bath, Somerset, the son of Arthur Bagenal and Magdalene Trevor, daughter of
Sir Richard Trevor of Trevalyn, Denbighshire. He was the grandson of
Henry Bagenal, Marshal of the Army in Ireland. He owned estates at
Plas Newydd in Anglesey and in
Newry, County Down. Bagenal was a commissioner of Assessment for Anglesey (1647–1648, 1660–1680), for
Caernarvon (1660–1663, 1664–1680), and for Anglesey and Caernarvon (1689–1690). He was elected MP for Anglesey in 1661, and was a Deputy Lieutenant (1661–?1680, 1689–1712) and
Custos Rotulorum for Anglesey (1689-1690). He was elected a
Fellow of the Royal Society in 1664. ==Legacy==