Boys in bottom right at PE are wearing the early flannel (white front) that was rather large, long and uncomfortable. They were changed to a more tailored article with shorter sleeves in 1932.

In the bottom left photo, note the watch stripes it seems the two boys to the left of the instructor are from port watch, one from 1st (one stripe) and one from 2nd (two stripes). Watch stripes were abolished in 1895 except for boys in training establishments and these lasted until 1907.