Downing Street Chief of Staff

The office of Downing Street Chief of Staff is the most senior political appointee in the Office of the Prime Minister of the United Kingdom, acting as a senior aide to the Prime Minister of the United Kingdom. The holder of the office retains a highly powerful, non-ministerial position within His Majesty's Government.

The role of Chief of Staff initially had executive authority, vested by the Prime Minister, and at the time of its inception, was referred to as the most powerful unelected official in the UK and possibly ranked third in government, after the elected Prime Minister and the Chancellor of the Exchequer. Since 2007, the role does not have legal or executive authority, although the post holder remains, by definition, the senior adviser to the Prime Minister, and controls access to the Prime Minister and their staff.

From 1997 to 2019, and from November 2020, the title of Chief of Staff has been held by the most senior special adviser at Downing Street. Steve Barclay, the Member of Parliament for North East Cambridgeshire, served as Chief of Staff from February 2022 to July 2022, following the resignation of Dan Rosenfield. He was the first MP to serve in this capacity, and also retained his position as Chancellor of the Duchy of Lancaster, and a Cabinet Minister, compounding the Chief of Staff's power and access in UK Government. On 24 July 2019, Dominic Cummings was appointed as a senior adviser to Prime Minister Boris Johnson and was described as the de facto Chief of Staff from 24 July 2019 to 13 November 2020 during the COVID-19 pandemic.

The incumbent chief of staff is Liam Booth-Smith, who was installed in the position by Rishi Sunak upon his accession as prime minister in October 2022.