Berragan was commissioned into the Royal Artillery in 1979. He went on to be Director of Military Training in December 2007, Director-General of Army Personnel in February 2011 and Adjutant-General in August 2012. Berragan was appointed Knight Commander of the Order of the British Empire (Knight Commander of the Order of the British Empire) in the 2015 New Year Honours.
He served as Chief of Staff of 4th Armoured Brigade during the Gulf War before becoming Commanding Officer of 32 Regiment Royal Artillery in 1997 leading his regiment on operations in Northern Ireland and Kosovo and then becoming Colonel in the Headquarters of the Adjutant-General responsible for individual training policy in 1999. He was appointed Assistant Chief of Staff, Training at Land Command in May 2004 and then saw active service as Deputy Commanding General, Multi-National Corps – Iraq from January to October 2007.
