The de Havilland D.H.9A, known affectionately as the “Ninak”, was introduced into RAF service in the last six months of the First World War and went on to become the Service’s reliable workhorse all over the world for the next decade. This example, J9124, was operated by No 30 Sqn, which flew the type in Mesopotamia/Iraq throughout the 1920s.

A pair of RAF officers pose with D.H.9A serial E8765, allocated to RAF North Russia (Southern Area) in 1919. Note the 112lb RL (Royal Laboratories) bomb in the foreground. The first RAF use of improvised gas bombs was undertaken by D.H.9s and D.H.9As at Yemtsa, the strategically important railhead on the Vologda-Archangel line, in late August 1919.

A clutch of 20lb general purpose bombs on the port wing of D.H.9A JR7825, which operated with No 14 Sqn in Transjordan.

A D.H.9A bounds across the valley floor taking off on another policing sortie in the Middle East. One intriguing report from a No 30 Sqn pilot in 1927 refers to a sortie in which practice runs were made with “Rains”. It remains a complete mystery as to what this refers to - perhaps a petroleum-based “sticky fire” like napalm?

A line-up of D.H.9As of No 55 Sqn at Hinaidi, Iraq, in 1926. In September 1920 the unit arrived in Mesopotamia (which officially became Iraq the following year) and spent the next two decades on policing duties in the country, largely made up of operations against raiding tribesmen. Regular claims have since been made that the RAF used chemical weapons in Iraq in the 1920s, but examination of the evidence suggests it is not true.

Special Brigade officer Lt Grantham holds a pair of “M Air Bombs” beside a Short 184 seaplane at Lake Onega, near Murmansk, in September 1919. The M Air Bomb incorporated diphenylamine chlorarsine and a thermogenerator which heated the chemical to create a highly toxic smoke that lasted for about two minutes, but which left no permanent effects.

A Hawker Audax of No 4 Flying Training School drops practice bombs filled with stannic chloride at Abu Sueir in Egypt in 1936. As stannic chloride is an oxide of tin, which was in short supply by the end of the First World War, it was sometimes substituted with a mixture of silicon tetrachloride and titanium tetrachloride, which had much the same effect.

Designed to incorporate as many parts from the D.H.9A as possible, the Westland Wapiti took over its predecessor’s role as a rugged, dependable general-purpose aircraft with No 84 Sqn in Iraq in June 1928. This Mk IIA fitted with a 550 h.p. Bristol Jupiter VIII engine was photographed at Hendon while serving with No 600 Sqn.