I know the guy that sold it, and have seen that sight. He had it mounted on a pristine
early 1900's No. 1, (like a 1910 or 1912, can't recall). I was fortunate to buy a couple of rifles from him. He has/had a world class collection. My No. 1 Mk VI came from him, along with my No. 4 Mk1 (T), and a few others. A very nice fellow, indeed.