Having graduated B.A. in 1624 and been ordained, Ambroses received in 1627 the little cure of Castleton in Derbyshire. By the influence of William Russell, earl of Bedford, he was appointed one of the king's itinerant preachers in Lancashire, and after living for a time in Garstang, he was selected by the Lady Margaret Hoghton as vicar of Preston. He associated himself with Presbyterianism, and was on the celebrated committee for the ejection of "scandalous and ignorant ministers and schoolmasters" during the Commonwealth.