No Markings means it was not a British Ordnance/British Government owned arm. Are there two small stampings top of the breech section of the barrel? If so, that would indicate the "Touch" and "View" inspections were done during proofing and could be a gun "made for the trade" by British Gun Makers.
If there are no markings at all, then that carbine was never proofed and therefore made outside what is now the UK. It may have been done in India, though more likely made in one of the Arms Bazaars in the Khyber pass or such places like it.
Gus
