The makers have kindly confirmed that the gun was completed in 1926.
This gun/rifle is in excellent condition and appears to have had very little use

The late LT Col. His Highness Maharao Sir Umed Singh Bahadur KCSI, GCSI, GCIE, GBE, ruler from 1896 of Kotah state, Rajputna, India, was clearly an enthusiastic sportsman for when he took delivery from William Evans of this shot and ball gun in 1926 it was one of an order for fourteen such weapons, eight ejector and six non-ejector. On the outbreak of the 1914-18 War the Durbar placed all their resources at the disposal of the British Government and in recognition of his services connected with the war The Maharao was further created GBE in 1918. Kotah state at the time covered well over 5 thousand square miles with a population of almost 7 million. The Maharao was entitled to a salute of 19 guns