I have to say, not having studied a C-No7 in any great detail, that the method of retaining a foresight block on a rifle by two cross pins (see large pics and Warrens pic above) is/seems to me to be totally unsatisfactory. Or in other words, what we Army types would call '..... its not soldier proof'. Just a bit careless and the foresight protectors would soon try to twist left/right and loosen that block.
That's just my 2c's worth after having given a few opinions during trials. I cannot believe that anyone would have got away with that method of retaining a foresight block. Even on the L42 it was sweated and they STILL broke loose occasionally!