In 1830 King George V died. William IV became King and asked Earl Grey to be prime minister.
Under Grey the third reform bill became law and this reorganised what constituted a borough so that towns previously not represented gained an MP or two and other places with MP but few voters, were emagulated into other boroughs. The number eligible to vote increased. With that achieved Grey happily resigned in order to retire.
I regularly make pots of Earl Grey tea which is named after him.