He was born at Etton in Yorkshire of a well-known gentle family. At 25 he went abroad to take part in the Dutch war. He visited Douay College to interview William Allen; a discussion led to his conversion, and eventually Andleby became a Catholic priest.
- "For the first four years of his mission he travelled always on foot, meanly attired, and carrying with him usually in a bag his vestments and other things for saying Mass; for his labours lay chiefly among the poor, who were not shocked with such things" (Challoner).
After about 20 years, he was condemned for his priestly character, and executed with three laymen, John Abbot, Thomas Warcop, and Edward Fulthrop.