Middlecoat joined the PAF, passed out of the 16th General Duty Pilot (GDP) Course in 1954, and won the Best Performance Trophy in ground subjects.

[2] Middlecoat's prowess as a pilot and leader were recognized early in his career and when Pakistan became the beneficiary of US military aid in the 1950s, he was selected, along with his close friend, Allauadin "Butch" Ahmed, to be the first two PAF officers to go to the US to train on the F-86 Sabre.

Besides undertaking dangerous photo-reconnaissance missions over Indian territory, including a key radar facility located in the grounds of a Sikh temple in Amritsar, Indian Punjab, he either shot down or badly damaged a high-flying IAF Canberra bomber egressing Pakistan airspace into India at night.

During the three-week war, Middlecoat flew 17 air defence sorties and three photo reconnaissance missions over forward Indian airbases.

[5] Promoted to Wing Commander, at the outbreak of war on 3 December 1971 Middlecoat was on a training assignment with the Royal Jordanian Air Force.

The day after he returned to Karachi, he volunteered for a mission to attack the heavily defended Indian airbase at Jamnagar on 12 December.

The Indian pilot who shot him down, Flight Lieutenant Bharat Bhushan Soni, saw Middlecoat eject and his parachute deploy.

As he fell into the Arabian Sea, Soni requested for a pass over the crash site to see where he had landed but was denied the permission to do so as his command already had the coordinates of the location to send a rescue team from the Indian Navy; however, by the time potential rescuers arrived, Middlecoat was nowhere to be found.

According to Soni, there is a 5 mile radius of shark infested waters at the area where the incident happened and Mervyn landed right in the middle of it.

[4] His citation read: On the outbreak of war on 3rd December 71, Wing Commander Mervyn L Middlecoat was on a training visit abroad.