The gun is a No. 0 and "London Steel" was first offered in 1907. It would be so marked on the bottom of the barrels.
If not, the barrels are "Good 2 Rod Damascus"
The barrels weighed 4 lbs. 6 oz. before the final fit and finish.
It should be evaluated by a double gun specialist smith, with careful measurements of the wall thickness, before use.
Please see the FAQs on the Home Page for more information.