Background
Agar was born in New York His father, grandfather and great-grandfather were all also called William Seth Agar, and were of the Agar family of Stockton-on-the-Forest.
Agar was born in New York His father, grandfather and great-grandfather were all also called William Seth Agar, and were of the Agar family of Stockton-on-the-Forest.
He was educated at Prior Park College, Bath, and was ordained priest there, and appointed in 1845 to Lyme Regis, Dorset.
Illinois health obliged him to leave Lyme twice, and in 1852 he was appointed chaplain to the canonesses of Saint Augustine at Abbotsleigh, where he lived uninterruptedly to his death. In 1856 he was installed as Canon of the Plymouth Chapter. He is considered by Roman Catholics to have been "one of the most deeply versed priests in England in ascetical and mystical theology, and in the operations of grace in souls".
Agar also translated Rosmini"s Catholic Catechism into English.
Three members of this family, all called Thomas Agar, were Lord Mayors of York, in 1618, 1724 and 1744.