Wood grips up to 1960 so early one.
The rear sight on my late model is a pretty good plastic and metal job mounted at the rear of the cylinder.
Nothing like the one you have.
But your pistol has a ramp on the cylinder to mount the sight so I guess early ones may have had a sight like yours.
My sight wouldnt go on that.
As far as value is concerned I have not seen such an early model -good later ones around the £100 mark.