From the outset, however, he displayed his opposition to the ideas of the French Revolution, and although this gained him favour with his friend Edmund Burke, it brought him little initial popularity.
A close friend of William Wilberforce, the leading light of the movement for the abolition of slavery, de Burgh enthusiastically supported the campaign.
Theophilus Lindsey resulted in the publication of A scriptural confutation of the arguments against the one Godhead of the Father, Son, and Holy Ghost produced by the Rev.
Thomas' son was General Ulysses de Burgh, 2nd Baron Downes, GCB (1788–1863), a well-known officer in the Peninsular War and aide-de-camp to the Duke of Wellington.
Margaret Amelia (died 1824) married John Foster, Lord Oriel, speaker of the Irish House of Commons, and was created Viscountess Ferrard in 1797.