William Lamb (1779-1848), the second son of 1st Viscount Melbourne, spent his childhood between Brocket Hall in Hertfordshire and Melbourne House, Piccadilly (now The Albany). In 1790, the year he went to Eton, he was painted, together with his brothers Peniston and Frederick, by Sir Joshua Reynolds, P.R.A., The Affectionate Brothers. After Trinity College, Cambridge, he was called to the Bar in 1804 which, after the death of his brother the following year, he gave up for politics. In 1805 he married Lady Caroline Ponsonby, only daughter of 3rd Earl of Bessborough and Lady Henrietta Frances Spencer, daughter of 1st Earl Spencer. Lady Caroline is today perhaps most famous for her relationship with Lord Byron. They were finally separated in 1825.
From 1806 Lamb held several different Parliamentary seats together with periods without office. In 1827 he became Home Secretary and (after succeeding to his father's titles in 1829) became Prime Minister for a few months in 1834. From 1835 until 1841 (save a brief period in 1839) he held office again initially facing opposition from King William IV but from 1837 working closely with the young Queen Victoria who held him in great favour.

The present sitter was painted three times by Sir Thomas Lawrence, P.R.A., the earliest portrait circa 1800 sold in these rooms, 10 December 1971, lot 90 (1,500 gns.) and now in the Devonshire Collection, Chatsworth.