W/Cdr Mermagen was born in Southsea, Hampshireon on 1st February 1912.
His interest in flight was first awakened when, as a child, he saw a Sopwith Camel land in a meadow near the family home.
He was educated at Brighton College, where he excelled at rugby, and in 1930 was granted a short service commission. Despite turning out for the RAF and Richmond Rugby Club at wing three-quarter, his short thickset frame had already gained him the nick-name of "Tubby".
In June 1931, Herbert was posted to 43 Squadron. There he revelled in the squadron's new Hawker Fury biplanes and displayed a talent for aerobatics. Having survived a tight formation touch with another Fury, Herbert was selected for the RAF aerobatic team at the 1933 Brussels Air Show.

Herbert was a natural for the Central Flying School (CFS), where he qualified as an instructor before moving to the Oxford University Air Squadron.
Then in 1936 he was posted back to CFS and the following year led the RAF inverted formation at the Hendon Air Display.

In 1937 he gave a solo aerobatic performance at Hendon for George VI. While still at CFS Mermagen was promoted Squadron Leader, an exceptional achievement in peacetime for a pilot aged 26. He was also given responsibility for assessing each new type of fighter or bomber before it joined operational squadrons.

In October 1939 Herbert Mermagen formed 222 Squadron, flying Bristol Blenheim fighters from Duxford near Cambridge.
In March 1940 he was ordered to convert the squadron to Spitfires, a task he carried out with such dispatch that he was awarded the AFC.
After Dunkirk, the squadron returned to Kirton-in-Lindsey, where on the night of 19th June, Herbert was credited with the probable destruction of an He111 bomber trapped by search-lights over Hull.
At the end of July 1940 he was ordered to form fighter stations at Speke and Valley. Herbert welcomed the posting as a break from writing letters of condolence to the relatives of those lost over Dunkirk.
In September he returned to operations at Wittering, where he led 266 Spitfire Squadron for a week. During this time he flew Spitfire P7350, now one of the Battle of Britain Memorial Flight.

In the summer of 1941, Herbert Mermagen (now a Wing Commander) was transferred to the Middle East. After arriving in Egypt, he commanded the fighter station at Port Said. He moved subsequently to Cyprus to lead 259 Wing, before taking up a staff appointment in 1944 at Supreme Headquarters Allied Expeditionary Force.
One of his last tasks at SHAEF was to help apprehend senior German officers including Field Marshal Kietel, General Jodi and Admiral Donitz. He also collared the Luftwaffe's General Koller at Berchtesgaden.

At the end of the war Herbert took charge of the British Air Command in Berlin where, as he enjoyed recounting, he experienced his only face-to-face encounter with the enemy during a mopping-up operation.

Herbert remained in the RAF after the war, serving in a variety of staff appointments and as air adviser to the British High Commissioner in Australia.
When he returned home in 1950, he qualified as a Gloster Meteor jet pilot while commanding RAF Leconfield. He moved on to Flying Training Command as Senior Administrative Officer and then went as Air Officer Commanding to Ceylon in 1955.

In 1960 he retired and joined the bullion brokers Sharps Pixley, staying as a director with the company when it became part of the Kleinwort Benson Group.

Mermagen was appointed OBE in 1942, CBE in 1945 and CB in 1960. He was personally invested by Marshal Zhukov with the Soviet Distinguished Services Medal in 1946. He also held the US Legion of Merit and French Legion d'Honneur.

Herbert Mermagen passed away in 1997 aged 85. He is survived by his wife Rosemary, whom he married in 1936, and their two sons.