Truss won 81,326 of the votes, while rival Rishi Sunak, the former finance minister, won 60,399, revealed Graham Brady, chairman of the 1922 Committee, the party council responsible for the process.

The result was expected and confirms the lead recorded in several polls published since July.

Truss, 47, will become the third woman prime minister of the United Kingdom, after Margaret Thatcher and Theresa May, and the fourth politician to hold the post in six years.

Boris Johnson will inform Queen Elizabeth II on Tuesday of his resignation from the post and the monarch will appoint Liz Truss and ask her to form government as leader of the party with a parliamentary majority.

The hearings will take place at Balmoral Castle in the north of Scotland, where the Queen is staying, breaking with the tradition of taking place at Buckingham Palace due to mobility problems.