William Brabazon Ponsonby Esq., later 1st Baron Ponsonby (1744-1806), was the grandson of Brabazon, 2nd Viscount Duncannon and 1st Earl of Bessborough (d.1758) and eldest son of The Rt. Hon. John Ponsonby (1713-1787), Speaker of the House of Commons in Ireland and his wife Lady Elizabeth Cavendish, daughter of the 3rd Duke of Devonshire. William Ponsonby was M.P. for Cork in the Irish Parliament from 1764 until 1776 during which time he was presented with this box. He was the M.P. for Brandon Bridge 1776-1783 and, after the general election of 1783, M.P. for Kilkenny, a seat he held until his creation as Baron Ponsonby of Imokilly on 13 March 1806, less than eight months before his death in London on 5 November.

A founder member of the Whig Club, Dublin, he was an Irish Privy Councillor and Postmaster General of Ireland, the latter post he lost after his support for the regency of The Prince of Wales, later King George IV, in oppostion to the Marquis of Buckingham. He married The Hon. Louisa (d.1824), daughter of Richard, 3rd Viscount Molesworth, in 1769. They lived at Bishop's Court, Co. Kildare, where they lived 'in the most hospitable and princely style'. He is said to have kept 'the best hunting establishment in Ireland'