PM sent. They are rare. I may be interested if you are selling. I already have one. Some sources think there were only a dozen or so made. I have serial #'s on about 6 as I recall. There was  a lengthly tread here several years back if you can find it with the search function. Mine has a Parker Hale liner and replacement British sights. Mine shoots well but I can't imagine reling a Stevens barrel but the British had their own way of doing things. They apparently didn't like it much because few were apparently sold. Would be great if you could post pictures here. From what I have found the 58 should be the serial #. Hard to tell what the other #is.

Seems like not really an expert, as private firearms ownership is still very much alive in the UK...

When I worked in Australia new gun laws based on the British model came in, about 1997 I think it was .  My firearms license was revoked had to re-apply. The license was issued to me not transferable to my wife or children. Had I passed the guns would have to go unless the family qualified, few widows were issued licenses. Large collection I knew of  intended as retirement fund was sold. Owner in poor health afraid his widow would have to sell to the government at set prices . It's possible the local police could have issued a widow license granting time to dispose of privately. Up to the authorities .

New license was controlled by the local police they could refuse for any reason. Too many guns without a "legitimate" use generally ment a quantity restriction. Collectors had to demonstrate collector value or de-activate the gun. At the time I had two Silhouette bolt actions rim and center fire, new license was approved. 

Smallbore prone rifle I was shooting belonged to the gun club. Local police said the club owned too many guns. They transfered the Anschutz 54 to me in order to reduce numbers. I had to have my license upgraded to 3 Rifles. Club sold half a dozen Martinis for export to further reduce.

There was no requirement to stamp with a club number very strict rules on storage and inventory private or club . Local police could enter my house at any time and inspect the guns and storage. Even inspect the size of bolts securing the required safe to the garage wall. No warrant no warning.

Vast numbers of Australian firearms were exported or destroyed, with government payment for set value.  

If a club target rifle was exported from the UK club marked the story is plausible One of our UK members may want to let us know if a similar situation applies . I do know a dealer in Front Royal Virginia imported large numbers of British club and school target rifles. Friend of mine and I were allowed to open a fresh packing  case full of rifles and associated parts.  It could easily have included a parts Stevens club stamped.

Boats.

Cartridge revolvers in certain "obsolete calibers" as named by the Home office may still be owned with no licence and no ammunition. Some counties still issue licences for the ownership of non-obsolete caliber handguns.