She married the Duke of Manchester on 16 April 1723,[1] about two years after he had inherited the dukedom.

There were two children from this second marriage: Isabella was one of the twenty-one 'ladies of quality and distinction' who supported Thomas Coram's efforts to establish a Foundling Hospital, who are now credited with making the endeavour a success by lending it respectability and style.

[3] She added her name to his petition on 6 January 1730, which was later presented to King George II in 1735.

[4] The Duchess was known as a talented amateur artist, who, according to Horace Walpole, "painted remarkably well in crayons".

Lord North confirmed that he had given such a promise in 1772, but the king, George III, would not go back on his word.