I agree with Bob Wright in that a real Webley should have enough markings to identify it as such. Webley was quite proud of their products and was not at all shy about putting their name and other identifying information on them. Consider the following pictures of my own Mk. IV:
First an overall view
Now the topstrap
The left side of the topstrap
The right side of the topstrap
And the Webley & Scott "flying bullet" logo on the upper frame just ahead of the cylinder on the right side
