Colonel George Sean Trengrove was born in Christchurch in April 1958. He was educated at Waimea College, Nelson.

Colonel Trengrove enlisted into the New Zealand Army in January 1975 as a Regular Force Cadet. During cadet training he was selected to undergo Officer Cadet Training at Portsea in Australia in January 1977 which followed a year spent as a rifleman in 2/1 RNZIR. He graduated in December 1977 into the Royal New Zealand Armoured Corps in the rank of Second Lieutenant. Colonel Trengrove was posted to the Waiouru Training Depot in December 1977.

In December 1978, Colonel Trengrove was posted to 1 Squadron New Zealand Scots, Burnham, and held the appointments of Troop Officer and Troop Commander. In February 1979 he was promoted to the rank of Lieutenant. In April 1980 Lieutenant Trengrove was posted to Queen Alexandra’s Squadron, Waiouru as a tank Troop Leader.  In February 1981 he was posted to 4 Troop 2 Squadron Scots as the Troop Commander.

In April 1982 Colonel Trengrove was posted to the School of Armour as the Senior Instructor and was promoted to Captain in December of the same year. In January 1983 he was posted to the appointment of aide-de-camp to the Governor General.

Colonel Trengrove returned to Army in August 1984 and was posted to the United Nations Truce Supervisor Organisation as a United Nations Military Observer. He returned to New Zealand in August 1985 to the appointment of Senior Instructor School of Armour, Waiouru.

In April 1987 Colonel Trengrove was posted on promotion to the rank of Major to Army General Staff, Wellington and held the appointments of Staff Officer Grade Two and the Assistant Military Secretary. In December 1989 he was posted to the appointment of Squadron Commander, Queen Alexandra’s Squadron, Waiouru.

In December 1991 Colonel Trengrove attended the Malaysian Armed Forces Staff College Haigate graduating in November 1992. He was posted to the All Arms Tactics Centre at Pulada, Malaysia as an instructor in the Senior Tactics Wing. Colonel Trengrove returned to New Zealand in November 1994 and assumed the appointment of Staff Officer Grade Two Operations/Plans, Army General Staff, Wellington.

In February 1996, while still posted to Army General Staff, he assumed the appointment of Director Army Resource Policy and was promoted to the rank of Lieutenant Colonel. Colonel Trengrove transferred to the Territorial Force in June 1999 and was posted to the appointment of Commanding Officer of the Canterbury, Nelson, Marlborough, West Coast Regiment in July 2000.  Completing that assignment at the end of 2002 he assumed the position of Assistant Chief of Army General Staff, Human Resources (TF) in the rank of Colonel.  He undertook a Regular Force engagement in 2005 as the Commander of 3 LFG and on his return to the TF assumed his current appointment of TF Advisor to the Land Commander.  In 2007-08 he served in Timor Leste as the NZ Senior National Officer and Deputy Commander of the International Stabilisation Force.

Colonel Trengrove and his wife Diane have four daughters.