In 1775 George Augustus Eliott, Lord Heathfield (1717 - 1790), was appointed Governor of Gibraltar. During the siege of 1779-83 he held the British fortress against Spanish attack, and was made Baron Heathfield in 1787. He is shown at Gibraltar during the siege, symbolically holding the key to the fortress, with a view to the peninsula in the background; a cannon points steeply down towards the sea and the sky is darkened by smoke. He is wearing what is presumably the ribbon and star of the Order of the Bath.
Lord Heathfield sat for this painting in August and September 1787. The portrait was commissioned by the print publisher John Boydell who paid for it in October of that year.