Lieutenant General William Neville Gardiner (23 April 1748 – 7 February 1806) was an Anglo-Irish army officer, diplomat, and politician.

During a career that spanned the 1760s to 1800s, Gardiner was involved in major historical events including the American Revolution, Partitions of Poland, and unification of Great Britain and Ireland.

Charles and Florinda had five children: In 1795, the Viscount Mountjoy title was recreated for Luke Gardiner.

When Luke was killed in the Battle of New Ross in 1798, the title passed to his son, Charles John Gardiner (1782–1829), who was later created the 1st Earl Blessington.

The 99th was disbanded when the Treaty of Paris was signed on 3 September 1783, and at this time Gardiner was put on half pay.

On 5 January 1792, Gardiner succeeded Daniel Hailes as the minister-plenipotentiary in Poland, having been recommended by his friend James Bland Burges.

His first task was to repair Britain's strained relations with King Stanislaus Augustus and his brother, Michał Jerzy Poniatowski.

In the Kościuszko Uprising, he assumed the role as the "unofficial leader of the diplomatic corps in Warsaw" and held regular meetings with the King.

Gardiner stood for the Irish House of Commons at Clogher, but was declared not duly elected on 3 February 1800.

William and Harriet had five children: During his time in Poland, Gardiner also had by an Irishwoman named Lucy O'Moore a daughter, Eliza Lila (1784–1849).