The proof marks should date it.

There are others on here who know more about them than I do.

A clear picture or sketch would be necessary to identify them.

Its not unusual for an original to turn up that has been on a wall or in a cupboard for years.
A gun club member saw a ramorod on a bootsale and asked if the seller had anything else and he mentioned he had a gun.
He went to see it and it was and original Enfield. It had been hung in the kitchen for years and the condensation had covered the outside of the barrel in small rust pits.
The bore was good and so he bought it and used it.