[4] Ponsonby was commissioned into the Royal Air Force in April 1983 as a pilot, after nine years service as an infantry officer in the British Army.
On 10 April 1983, he was appointed to a permanent commission and promoted to flight lieutenant[5] with seniority from 10 March 1980.
[8] As a group captain, he was appointed an Officer of the Order of the British Empire in the 1999 New Year Honours,[9] and was made an aide-de-camp to Queen Elizabeth II on 1 August 2001.
It was announced on 16 January 2007 that Ponsonby was to be chief of staff operations, Headquarters Air Command, from July 2007.
He chose instead to leave military service to take a commercial role as senior vice president training, AgustaWestland.