Gunners of the Hong Kong and Singapore (Mountain) Battery, Royal Garrison Artillery with their BL 2.75-inch mountain guns dismounted, re-assembled and ready to fire. Despite their unit title, the battery's personal were in fact drawn from the Indian Army. To the rest of the Imperial Camel Corps Brigade, the battery and its gunners quickly became better known by their nickname 'The Bing Boys', apparently bestowed in imitation of the toy-like metallic ringing noise their mountain guns made when they were fired.
The BL 2.75-inch (70-mm) calibre mountain gun could fire shrapnel and high explosive (HE) shells out to a range of 5,600 yards (5120 m) and 5800 yards (5300 m) respectively. It was a comparatively modern design having only been accepted into service by the British Army in 1914, when it was chosen as a replacement for the obsolescent 1901 BL 10-pounder mountain gun. Due to its specialised function the need for the BL 2.75-inch mountain gun was very limited and only 183 were built during the entire war (by contrast just over 9000 18-pounder field guns were produced for the British Army during the same period).