[1] During the reign of Charles I, he sold a great number of guns to the former United Provinces, with the King being a partner in this traffic.
One such cannon made by Browne was recovered from the wreck of the English ship Swan, a 200 long tons (200 t) Cromwellian warship lost in a storm off the Isle of Mull in 1653 whilst attacking Duart Castle.
It fired shot weighing 4 pounds (1.81 kg).Swan was the last ship built for Charles I, and its guns were all cast in iron.
In 1645, John Browne and his son were ordered by Parliament to be taken into safe custody, and no visitor was allowed to be alone with either of them because he was suspected of supporting the Royalist cause.
[5][6][7] Browne's wife, Martha, is commemorated by a cast iron graveslab in St Margaret's Church, Horsmonden.