He was born in Etton, Yorkshire into a gentry family. At 25 he went to the Netherlands to take part in the Dutch war. He visited Douay College and met 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 as a Catholic priest. He was executed with three laymen, John Abbot, Thomas Warcop, and Edward Fulthrop.