Was James gregson a ship owner?

Yes indeed he was a Liverpool ship owner, who infamously owned with others, the schooner Zong. In 1781 the captain of this slave trader threw 133 slaves into the mid Atlantic in order to claim the insurance money for the ship owners rather than the 'cargo' being reported dead on arrival with no claim possible. The case was central to highlighting the inhumanity of the slave trade and greatly helped in it's abolition in 1807.