Jeremy Corbyn assumed the position of Leader of the Opposition after being elected as leader of the Labour Party on 12 September 2015; the election was triggered by Ed Miliband's resignation following the Labour Party's electoral defeat at the 2015 general election when David Cameron formed a majority Conservative government. The usual number of junior shadow ministers were also appointed.

The Leader of His Majesty's Most Loyal Opposition, more commonly referred to as the Leader of the Opposition, is the person who leads the Official Opposition in the United Kingdom. The position is seen as the shadow head of government of the United Kingdom and thus the shadow prime minister of the United Kingdom.