When Gilbert was aged 19 his father died and he left his apprenticeship to superintend the family lime works.
John's brother, Thomas, was working as agent to Lord Gower, brother-in-law of the Duke of Bridgewater.
[1] Around 1758 John was appointed as the Duke's agent and moved to live in Worsley.
As separate undertakings, Gilbert worked on the drainage of Martin Mere and in the reclamation of the northern portion of Chat Moss.
[3] At the time of his death work was proceeding to his design of an inclined plane within the Worsley mining system.