Not much is known about his early life, though by the time he was 50 years old, he was a leading citizen of the town, having undertaken the roles of timber merchant and shipbuilder. His yard was on the south of the Salthouse Dock, Liverpool, and over the years he would build many coasting brigantines and sloops in alliance with William Marsh. The first was the "Hastings", a ship of 44 guns and weighing 682 tons.
He would build another eight ships between 1740 and 1758 for the navy.
His shipbuilding company saw several other partners over the years: by 1758 the firm was "Okill and Rigg", and in 1768 it became "Okill & Sutton". Though many of the other merchants traded in African slaves, Okill"s was the only firm to take no part in the slave traffic, which instead "traded in wood and teeth (ivory)".
In 1747 Okill was the donor of the lease for the site upon which the original Saint Thomas"s Church was built. In 1773 he started work on a manor home in Woolton called Lee Hall.
There were problems associated with the disposal of John Okill"s estates, requiring an Acting of Parliament in 1784, (24 Geo III, c 1) to enable the trustees to dispose of certain of them.
James and his inheritors, the Dutton family, helped to plan and layout what would become Gateacre. There was a monumental inscription to him at original Saint Peter’s Church, Liverpool. Lee Hall was torn down sometime after 1971.
His commercial Day Book for 1752 – 1753, listing the daily transactions relating to his shipbuilding business can be found at the Liverpool Record Office and Local History Service.
Liverpolitana, Williams, Peter. Merseyside Civic Society.