He was a lawyer, who also served as Baron and Chief Baron of the Exchequer, with considerable experience of rivers and watermills.  Fray had the commision for maintaining to navigation of the River Lea, and owned watermills in Essex and interests in other property across the country.  This included Cowley Hall, which adjoined the Frays River, a branch of the River Colne.  It is said that John Fray arranged the cutting of a link from the Colne to a tributary rising in Harefield to increase the water volume.