Mayall was educated at Street George"s College, Weybridge, Balliol College, Oxford (Bachelor Modern History, 1979) and King"s College London (Master of Arts International Relations). After that he completed a Defence Fellowship at Street Antony"s College, Oxford studying Turkish security policy.
Mayall was commissioned into the 15th/19th The King"s Royal Hussars in 1979. From 1985 to 1988 he was seconded to the Sultan of Oman"s Land Forces. He was operations officer for 1st Armoured Division in the first Gulf War.
He then became Commanding Officer of 1st The Queen"s Dragoon Guards in 1997 in which capacity he was deployed to the British Army Training Unit Suffield and to Northern Ireland.
In 2001 Mayall became Commander of 1st Mechanised Brigade which was subsequently deployed to Kosovo. He was appointed Assistant Chief of the General Staff in January 2007 and in 2009 became Deputy Chief of the Defence Staff (Operations).
He was made Defence Senior Advisor Middle East at the Ministry of Defence in May 2011. He will be replaced in that role by Lieutenant General Tom Beckett in late 2014.
In 2015, Maywell retired from military service and joined Greenhill & Company, an investment bank, as a senior advisor.
