I'm afraid that, in my opinion, this is a real 'put together' helmet made from a miscellany of parts which don't go together. The helmet plate is a Victorian period 'other ranks' plate, and the combination of the brass plate and white metal centre with no battle honours on the arms of the cross indicates, I believe, a militia battalion of the Border Regiment. The cross on the plates of the regular battalions bore the regimental battle honours. Things go down hill from here, I'm afraid. The Border Regiment was an infantry Regiment and both the grey cloth helmet and the 'ball' are wrong for the regiment. They, like most other infantry regiments, wore 'blue cloth' helmets with a spike. This helmet looks like an 'other ranks' helmet to a volunteer rifle regiment as they wore this type of 'grey cloth', with a spike. The ball was worn by artillery and the various Corps of the British army, other than the Royal Engineers. The rosettes, too are wrong -these type of 'lion head ' rosettes were worn by lancer regiments and one or two heavy cavalry regiments. Finally, the mark left on the helmet when the plate is removed doesn't, at least to my eyes, look to have the same outline as the plate.
Sorry about this. Does anybody else see it differently?
Patrick