Thanks lads. With a name to go on Griffiths book becomes much more informative. Judging from the single action pin, squared off trigger aperture, and a tang on the rear RHS grip, its a "Dolla" variant 3.

The tang, though its not come out well on the picture



There is a breech plug, whether it is the original I could not say,





but it looks very similar to Griffiths illustration on p68