If it is actually stamped "Webley & Scott" it would have to be after 1897.
Webley made all sorts of single shot rifles - break action, falling blocks (Field patent, Farquharsons, 1897 patent, '02 patent) as well as pivot block Wyleys (which should pre-date your gun) and all types of Martinis.

I look forward to your further report and pictures!