It is an Enfield pattern short rifle for rifle regiments and for sargeants in other regiments.
Any  muzzle loading firearm made before 1939 is an antique and can be kept "as a curio or ornament" unless you want to shoot it. Then it has to be put on an FAC for rifles and pistols or on an SGC for a shotgun.

The proof marks are interesting. Not that I am an expert but it appears to have been reproved under the London rules of proof after 1925. 

The marks from left to right read,
No 1, Preliminary black powder proof (lion over a fancy letter G).
No 2, View mark(crown over V).
No 3, Bore size. 25 bore approx, .577.
No 4, Final black powder proof for use with nitro powders or in this case, final black powder proof for smooth bore muzzle loaders (crown over intertwined CP).

The reproof marks (if that what they are) suggests to me that it may have been smooth bored in the 1920's perhaps to be kept without having to apply for an FAC as was required for all rifles and pistols after 1920. Or to be used as a shotgun which did not need any police authority to be kept and used. Any removal of metal on the barrel required a reproof.

GJ
    

Paul nice find,if you want to check the rifle for rifling this can be done by having a tight cleaning cloth on a rod and watching for the rod to turn as it progresses down the barrel.you can put a chalk mark and watch for it turning.Take care not to lose the cloth down the Barrel.
The rifle is antique and absolutely legal to own.If you wish to shoot it, it must be put it on a Firearms Certificate.
                                        Regards.

West Hallam near Ilkeston.
Steel wool on a rod should derust sufficiently to check for Rifling.
                    Regards.

Hi Paul,

I know you are trying to move this rifle on but the following link should be of interest and will give some more insight into the stamps and markings:

http://www.enfield-snider.com/Markings%20-%20Barrels.htm

As GJ says from his post...This is covered by section 58a of the 1968 'Firearms and Licensing Act' which classifies this as an antique and this can be owned by anyone as essentially curio. If you intend to use it as a 'gun' then it requires Section 1 authority on your license...

As an antique it can easily be posted to a purchaser (I have used 'TNT' and 'parcelforce' in the past) should you go down that route....

Did you manage to work out if it has been smooth bored?

Regards Jon

As I understand it, lining the barrel back to .577 rifled would require a reproof and make the gun a section one firearm requiring it to be on certificate.

As this is configured as a rifle with proper rifle sights, I suspect that it is still rifled and the owner has not yet cleaned and examined the bore sufficiently.  When these rifles were smoothbored for use as shotguns the sights were normally taken off.

There is a possibility, if it has been smoothbored, that someone before the war was conforming to the 1937 Act which required a licence for rifles and at that time the police generally accepted only flintlocks as genuine antiques. Pure speculation and, in any case, I would want to see a full set of photos with ALL marks and to hear just exactly what is the state of the bore.

I am pretty sure that I can see rifling under all that rust. What you need is a small pen light torch which you drop down the barrel and that will show it even if it is rusty. This type of rifle has very wide shallow grooves, either three or five in number.