I think the production figures are listed in the "The British Falling Block Breechloading Rifle from 1865" by Jonathan G. Kirton as well as in the multi-volume work on individual mfgs, in the first volume of the five now out, "British Single Shot Rifles, Vol. 1; Alexander Henry" By the way, in the list shown in this first volume, you will see that Alex Henry made more than all other mfgs. After he died right at the beginning of the NE era, the company was absorbed by others and the single shot focus seemed to shift to Gibbs and others. Still, if you look through the various catalogs all through the first two decades of the Twentieth Century, Westley Richards, H&H, and a few others always had single shots listed for sale, including more than a few in the 500, 577 and 600 NE class. A very British, and very long-lived creature. They are survived today by the Ruger No. 1, the Hagn, the Dakota 10 (offered in some fairly stout loadings) etc but no longer built in Britain. Strange, but the Single Shot tradition is as the American (or, considering Hagn, Canadian via Rolf and Martin's German training)as Apple Pie and has strong roots on the Continent as well. Dave