Having completed his first tour in the FAA and returned to Corps Duty, Gerry Martyn realised that without a specialist qualification life in the Corps meant a succession of sea going appointments as OCRM. He therefore, applied for the long Gunnery course at Whale Island and qualified in 1935. Then followed command of an AA Section in the MNBDO at Alexandria after which he was AI of G at Plymouth in 1936.
It seems likely that the two qualifications of Pilot and I of G led to the next phase in his career. Following the Inskip Report of 21 July 1937 full control of the Fleet Air Arm returned to the Admiralty which became responsible for training, organisation and equipping the FAA. By 1938 the expansion was in full swing and the "A" Branch had been formed for pilots and observers and soon the Navy would have full control with its own shore stations. At this stage Martyn was invited to return to the FAA and specialise as an Armament Officer with a twelve months course at RAF Manby. On completion of this he was appointed to the staff of Rear-Admiral Naval Air Stations at Lee-on-Solent. By this time he held the dual rank of Captain RM and Squadron Leader RAF so that when airborne he was senior to himself. However, dual ranks ceased in 1939.
Although Manby had filled him with theories on the terminal velocities of bombs and the striking power of bullets he was little prepared for the problems to be solved in the FAA. Although the air stations had been taken over, the gunnery side of the Navy had not been concerned and no arrangements existed for taking over of the armament stores, known as Vote 9 stores. In a ship there would have been a Gunner but at Lee there was no one. The Naval maintenance staff had not yet been trained and only a few RAF ranks remained. Fortunately a few ordnance artificers had been drafted and for the next four years they were the mainstay of the FAA armament work.
As air stations were taken over or opened it was found that no arrangements existed for air gunnery training ranges and these had to be improvised at first at St. Merryn in Cornwall and in Lyme Bay at Haldon. Training of air maintenance personnel took place at Lympne until France fell and instructors for the Ordnance side were found by calling up ex GI's and GM's including one RM who was later promoted to Lieutenant for his work on bombs in the Department of Naval Ordnance.
After a time, he moved to the Air Material Department to carry on solving the problems of catering for the demands of new aircraft carriers, CAMships, and air stations at home and abroad and it was finally decided to bring it all under the Director of Naval Ordnance with a proviso that Major Martyn was included. So in 1943 he joined the DNO. Changes in training were now made so that Armament Officers became "Air Gunnery Officers" and their training took place at HMS Excellent. By this time a team of Air Gunnery specialist had been built up around the original nucleus of Gerry Martyn and their combined ideas began to bear fruit. By 1944 Martyn realised that there were enough men now available who had first hand experience and he decided that it was time they should be brought in. Hence in December 1944 he reverted to Corps Duties.
For the next three years he was involved with the 34th Amphibious Support Regiment, India. Java and North Devon followed by three years at ITC.
He retired in 1954 but was re-employed on recruiting duties at Bristol and in 1957 became CO RMFVR at Bristol until 1959.
He finally retired in 1964 in his own words "with rank of Major and pension of Captain RM but given Honorary rank of Lieutenant Colonel".