& say I think it's a good one. The appearance of the wood is quite typical of late issue WW2 walnut as is the manufacturer of it. I would concur with Peter's comments but would also state that I'm sure the forend stamps (even with the circle around them) are consistent with being original. When I bought the batch of T's in the 90's I also bought several sacks full of 'take off' wood. This varied from mint to well used & there were a number of forends identical to that shown (save for the serial number itself, of course). Re the S51 ----- yes it is a little atypical in its spacing, but they were all hand stamped don't forget, & the S & the 51 are all of the correct style.
The only thing that I don't like about it is the price.......
ATB