They are members of the Gold Coast Constabulary or Haussas, in a form of undress.
Essentially that means they are not wearing the zouave style waistcoat over the jacket show, and the jacket is not tucked into the trousers.
Almost the entire uniform is dark blue, with red braid embellishments.
It is indeed at the Jubilee celebrations of 1897
Would love to attach a drawing of mine but I can't figure it out