Evening all, thanks for your posts and interest, I may have a break through; a member of a diferent forum has suggested that as the helmet has a ball, not a spike "it may be a Volunteer Medical Staff Corps officers helmet. Kipling shows the MSC and RAMC victorian officers helmet plate made up of royal arms and scroll below with "Royal Army Medical Corps", but from photographs of the period all the medical officers blue cloth helmets show the plate as being royal arms only. This plate was worn by Medical Staff Corps, Medical Department and post 1898 Royal Army Medical Corps in Gilt and in Silvered/white metal by the volunteer units."
A second opinion is always welcome but that does seem pretty concise.
