Louise Haigh was once described as having “terrier-like intensity” after she was first elected as an MP for Sheffield Heeley in May 2015.

Then-House of Commons speaker John Bercow praised her for her campaigning against the closure of tax offices and the following year she was deemed by the Yorkshire Post to be the most hard-working of the new intake of MPs because of the volume of her parliamentary questions and speeches.

Born in 1987 in Sheffield, she studied politics at Nottingham University and law at Birkbeck, University of London.

She worked as a shop steward for the union Unite and as a Metropolitan Police officer in London’s Lambeth borough before entering politics.

Ms Haigh has said she drew on her experience as a special constable when she was shadow policing minister from 2017.

The 37-year-old has called for changes to the culture of policing.

She nominated Jeremy Corbyn in the Labour leadership contest in 2015 but then backed Owen Smith, and campaigned for Lisa Nandy rather than Sir Keir Starmer to be Labour leader in 2020.

But she still remained in high-level roles within the party.

Ms Haigh was made shadow secretary for Northern Ireland in 2020, at a time when tense post-Brexit trade negotiations were taking place, before taking up the shadow transport secretary post in 2021.

Ms Haigh was appointed Transport Secretary on July 5 2024 after Labour’s general election win, becoming the youngest female Cabinet minister to ever be appointed.

In October, Ms Haigh said that she had boycotted P&O Ferries and encouraged others to do so, after the firm sacked hundreds of workers in 2022 and replaced them with lower-paid agency staff.

The Prime Minister publicly criticised the comments, saying they were “not the view of the Government”.

During the election campaign, Ms Haigh pledged to bring train services on Britain’s railways into public ownership.

A day before her resignation, flagship Government plans to renationalise rail passenger services became law.

The Passenger Railway Services (Public Ownership) Bill received royal assent and will enable the Government to take over services from private firms as their franchises expire or are broken.

Ms Haigh said it marked “a historic moment for our railways”.