Gray joined the Engineer Branch of the Women's Royal Air Force in 1985. She was promoted to flying officer on 18 February 1986, and to flight lieutenant on 18 February 1989. In 1991, she was deployed with the Support Helicopter Force to Iraq as part of the Gulf War. On 15 June 1992, she moved from a Short Service Commission to a Permanent Commission, and therefore extended her service time to retirement age. In 1994, the Women's Royal Air Force merged into the previously all-male Royal Air Force. Since then, Gray has served in the RAF. On 1 July 1994, as part of the half-yearly promotions, she was promoted to squadron leader. On 1 January 2001, as part of the half-yearly promotions, she was promoted to wing commander. In 2003, she was once more deployed to Iraq, this time as part of Operation Telic and served as Chief Engineer for the Joint Helicopter Force.
Air officer
Gray was appointed an Officer of the Order of the British Empire in the 2005 New Year Honours and, on 1 January as part of the half-yearly promotions, she was promoted to air commodore. On 29 January 2014, Gray was promoted to air vice-marshal and appointed Director of Combat Air at Defence Equipment and Support in the Ministry of Defence. In that role she was "responsible for the procurement and maintenance of all combat aircraft, training aircraft and remotely-piloted air systems for the armed forces". She is the second female officer to be promoted to non-honorary two-star rank in the British Armed Forces since the Second World War; the first was Elaine West who had been promoted to air vice-marshal in August 2013. In February 2016, it was announced that she would be the next Air Officer Commanding No. 38 Group. She took up the appointment on 16 June 2016 in succession to Tim Bishop. Gray was appointed a Companion of the Order of the Bath in the 2017 New Year Honours, and was elected a Fellow of the Royal Academy of Engineering. She handed over command of No. 38 Group to Air Commodore Simon Ellard in December 2018. On 20 February 2019, it was announced that Gray had been promoted to air marshal, and thus becomes Britain's first ever female three-star officer: she thereby became the most senior female officer in the British Armed Forces. Since March 2019, she has been the Director General of the Defence Safety Authority. Gray is a recipient of three campaign medals; the General Service Medal, the Gulf Medal, and the Iraq Medal. She is also a recipient of the Queen Elizabeth II Golden Jubilee Medal and the Queen Elizabeth II Diamond Jubilee Medal. With the change in rules in 2016 making all officer eligible, she was awarded the Royal Air Force Long Service and Good Conduct Medal in recognition of 15 years service.
