The constituency of Westminster contained Whitehall, the Houses of Parliament and Buckingham Palace. It was also an area where the nobility had their "town residences". However, it was one of the few boroughs that allowed all householders who paid the poor rate to vote in parliamentary elections. As a result of its broad franchise, the Westminster electorate was unusually large. By 1820 over 20,000 people had the vote in Westminster and many of them held Radical political views.

Charles Fox, the leading Radical Whig in the House of Commons, represented Westminster between 1784 and 1806. Another Radical, Richard Sheridan won a bitterly fought campaign in 1806. Two Radicals, Thomas Cochrane and Sir Francis Burdett, were elected in 1807. When Cochrane retired in 1818 he was replaced by another Radical, John Cam Hobhouse.