[4] On 8 March 2022, Harrington was appointed Minister of State for Refugees, with his ministerial portfolio being in charge of co-ordinating the UK's response to the humanitarian crisis caused by Russia's invasion of Ukraine.

[5] In August 2022, the government announced that, under Harrington’s leadership, a total of 104,000 Ukrainian war refugees had been given safe refuge in the UK.

[6] On 4 September 2022, Harrington stepped down from the role, having completed the task of putting in place a permanent system for arrivals.

[9] Chancellor of the Exchequer, the Rt Hon Jeremy Hunt asked Harrington in April 2023 to lead a review of the government's approach to attracting foreign direct investment into the UK.

[12] He began his career in business with a graduate scheme at the John Lewis Partnership, where he eventually became the assistant to the managing director of Waitrose; this included a period working at Trewins Department Store in Watford.

Other notable work in property development included the restoration of one of Glasgow's most famous hotels, One Devonshire Gardens.

Until March 2010, he was chairman of the Executive Board of the Conservative Friends of Israel, which, during his tenure, had quadrupled in size financially.

[12] He was appointed a treasurer of the Conservative Party in 2008, the role in which he launched the Number 10 Club with Sir John Major.

[18][19] Since his election to Parliament, Harrington has also been elected as General Secretary of the All Party Parliamentary Kashmir Group (until 2015), Vice Chairman of the All Party Parliamentary Film Industry Group, and a member of the International Development Select Committee between July 2010 - November 2012.

In the 2012-13 Parliamentary Session, Harrington successfully brought in a Private Members Bill to criminalise the unlawful subletting of social housing property.

Harrington was appointed Parliamentary Under Secretary of State at the Department for Work and Pensions in Theresa May's first Cabinet reshuffle on 17 July 2016, with his former position left vacant and effectively abolished.

In March 2023, the Chancellor, Rt Hon Jeremy Hunt, asked Harrington to Chair a review into Foreign Direct Investment.

This led to its publication in November 2023 with a series of recommendations reorganising the government in a cross department, investment friendly way.