[1] Largan's father came from a large Irish Catholic family in Salford and had a variety of occupations, including a Shabbos goy, plasterer, postman, and trade union shop steward.

His mother left school with no qualifications, caring for her younger sisters following the death of her father, and later worked in the Department of Social Security.

Largan began his political career with the Conservative Party in 2014, gaining a seat as a local councillor for Sands End in Hammersmith and Fulham London Borough Council.

[9] At the 2017 general election, Largan unsuccessfully contested the Bury South constituency for the Conservatives, where he finished second with 41.6% of the vote behind the incumbent Labour Party MP Ivan Lewis.

In his role on the committee, he contributed to inquiries into various issues, including the impact of the coronavirus pandemic on the aviation sector and the rollout and safety of smart motorways.

[14][15] Largan gave his maiden speech on 23 March 2020, during an emergency debate on the Coronavirus Bill which introduced a range of new powers to tackle the Covid-19 pandemic.

[3] In November 2020, he founded the All-Party Parliamentary Group for the Peak District and was elected chair, noting a focus on bringing green jobs to the region.

[16] After backing frontrunner Rishi Sunak in the second Conservative leadership election,[17] Largan was appointed Assistant Government Whip on 25 October 2022.

[34] In July 2021, Largan successfully brought an extension to the now paused controversial Clean Air Zone, to include all roads into Mottram and Hollingworth.

[35] In September 2021, Largan raised the issue of increasing access to face-to-face GP services at Prime Minister’s Questions, citing cancer diagnosis as a key concern.