This photograph may have originally been arranged on a page grouped together with other photographs labelled "Sikhs", with each having an album/mount caption, as per Elizabeth Edwards and Ella Ravilious in 'What Photographs Do: The Making and Remaking of Museum Cultures' (pages 142–143, 21 November 2022, ISBN: 9781800082984), available for free download via: [1]

Quote from the above discussing this:

A particularly notable discovery was a group of calotypes of Burmese architecture and people. Some were beautifully composed, but in general there was a sense of amateur experimentation about them. One of them was mounted on white paper with the handwritten title ‘Great Pagoda Prome (very ancient)’; however, of much greater interest to me was the reverse of the page. Here were nine empty spaces with torn sepia remnants where whole photographs had once been; each of the spaces was marked with an accession number, and the group was titled ‘Sikhs’, with the central image ‘Maharajah’. This was probably the result of a misguided attempt to lift the images from the page and potentially rearrange them according to new evaluations such as separating architecture from people, but I recognised this as a significant loss. Cultural knowledge enabled their identification as the earliest photographs of the Sikh people and their ruler Duleep Singh. The acquisition registers revealed that Dr McCosh deposited them in the Art Library in 1884, and subsequent research identified them as extremely rare prints by Dr John McCosh (figure 8.3).