Who is who on this photo?
Sir Tharia Topan is the big (Indian Ismaili ) gentleman located front-row right. Tharia Topan:
Person top-row right is Sir Bartle Frere and several high ranking British naval officers.
The key person in the middle of the front row could be:
The Omani official on the front-row with his sword is also unknown, almost certainly a member of the Sultans family (he could be Hamad bin Thuwaini who became sultan in 1893)
Hamad bin Thuwaini at later age , became Sultan in 1893
and was probably poisoned a few years later.
Most of the officials on first photo are also on the next stone-laying photo. The uniforms worn by the British naval officers were phased out before 1890.
It was Bartle Frere who in 1875 persuaded Bibi Salme (Emily Ruete) not to contact her brother Sultan Bargash (about her inheritance) during the Sultans visit to London, with a promise of financial support for her children. However the British did not keep word.