[1] Some writers refer to the 2.5-inch gun as a "7-pounder" because it also fired a shell of approximately 7 pounds, but its official nomenclature was 2.5-inch RML.

The Elswick Ordnance Company made 12 Mk I guns based on his design and they were trialled in Afghanistan in 1879.

Trials were successful and Mk II with some internal differences made by the Royal Gun Factory entered service.

[1] A major defect in the war was that the gun's cartridges still used gunpowder as a propellant, although smokeless cordite had been introduced in 1892.

Either 4 or 6 guns (sources appear imprecise) were returned to service from Southern African garrisons in 1916 and were employed by the Nyasaland-Rhodesian Field Force in the campaign in German East Africa.