In 1809 he was commissioned as Lieutenant-Colonel Commandant of the Bearsted and Malling Regiment of Local Militia.

According to the Legacies of British Slave-Ownership at the University College London, Romney was awarded a payment as a slave trader in the aftermath of the Slavery Abolition Act 1833 with the Slave Compensation Act 1837.

Romney was associated with three different claims, two of which were successful, he owned 432 slaves in Saint Kitts and Nevis and received a £7,268 payment at the time (worth £871,245 in 2025[4]).

[1] They had one son and four daughters: Lady Romney died in September 1812, shortly after the birth of her youngest child.

On 8 February 1832 Lord Romney married secondly the Hon Mary Elizabeth Townshend,[1] daughter of John Townshend, 2nd Viscount Sydney and widow of George James Cholmondeley.