The Crowley Iron Works at Winlaton, Winlaton Mill, and at Swalwell, all in County Durham were probably, at the time, Europe's biggest industrial location and later, as he was owed so much money by the British Government, Ambrose became a director of the South Sea Company on its formation. Today, he is still known for his enlightened management methods. His workers had an elected works committee, sickness payments, company medical team and were treated with respect. These rules are set out in the 'Rules of the Crowley Iron'. The main works at Winlaton mainly used imported iron and both iron and steel were worked by the Heyford process. Technologies and skills developed at Winlaton were to lead to the foundation of the Sheffield steel industry and to the ability to machine steel. British iron production was carried out at Ynyscedwyn in South Wales and in the Wealden area of Southern England. The business survived into the Victorian era and the 'Crowley Crew' were renowned for their skills with metal and their steadfast and resolute defence of their rights and freedoms in the face of government intimidation.
Ambrose married Mary Owen, daughter of Charles Owen. They had many children die young. His wife's memorial lists seven children who died as infants. The children that lived to adulthood were as follows: John Crowley who married Theodosia Gascoigne; Mary who married Sir James Hallett; Lettice married Sir John Hynde Cotton, 3rd Baronet; Sarah married Humphry Parsons; Anna married Richard Fleming; and Elizabeth to Lord St John of Bletsoe.
NEAR THIS PLACE ARE DEPOSITED THE REMAINS OF SIR AMBROSE CROWLEY KNIGHT, CITIZEN AND ALDERMAN OF LONDON, WHOSE NUMEROUS FAMILY AND GREAT ESTATE WERE THE PRESENT REWARDS OF AN IDEFATIGABLE INDUSTRY AND APPLICATION TO BUSINESS, AN UNBLEMISHED PROBITY, AND A SINCERE BELIEF AND PRACTICE OF TRUE CHRISTIANITY, AND PARTICULARLY A BOUNDLESS LIBERALITY TOWARDS THE POOR, MANY HUNDREDS OF WHOM HE CONTINUALLY EMPLOYED.
- M. W. Flinn, Men of Iron (Edinburgh, 1962).