Yes, exact same rifle.
Thanks for the link GG.
Rassie Erasmus of Bredell, South Africa. Duly noted, thanks all.

BTW, took a while to get through the thread on that "other" site, 3 pages of mis-information before Matt got the details via another source anyway...

A couple of photos are up on that other site, so I will endeavor to add pics of the Blenheim sight here when I get a chance. Should be of interest to those us us building big-bore bolt-guns. Meanwhile, a preview from another website to tide you over.