Yep, that's him seated bottom right....with the trumpet...of course! VERY sad about Clive. Thanks Annie,
This is old NSW Government House Barracks and Stables (where they lived and were born) with the new Conservatorium Of Music next to it today.
You probably have this already Mike ... but just in case !! .....

Another interesting appointment in 1887 was that of Charles Albin Dalton, son of Senior Sergeant Dalton of the police ( mentioned above ) .... C. A. Dalton was born at the Government House stables and his soldiering commenced at the age of 14 when he joined the artillery as a trumpeter; when he was 16 he transferred to the newly formed Sydney Light Horse and rode in the escort on March 3 1885. In 1887 he enlisted as a permanent soldier and was appointed to the permanent staff of the cavalry as trumpet-major and orderly room clerk (General Order No. 128). He was a man of strong character and a keen soldier. After about 20 years with the regiment he was transferred to the Mounted Rifles as regimental sergeant-major and later helped to train light horsemen in Victoria and Queensland also. He was the only original member to witness the regiment's Diamond Jubilee parade in 1945
http://authenticrepro.com/lancers.htmlName - Clive Malcolm Dalton, Sergeant, 4th Australian Light Horse died 12 Aug 1915 age 21. Parents - Son of Charles Albin Dalton and Amy Dalton of Victoria Barracks Sydney NSW. Burial - Alexandria Egypt.