I stand corrected; it does looks similar. No doubt an idea that was tried before Long Branch produced their "Monte Carlo" buttstock. As it is described as "moveable" in the book, perhaps it had inset threaded plugs in the butt to enable the user to move it without resorting to the services of an armourer. Just a guess, but there would be little purpose otherwise, although to my eye, it would do a better job of supporting the shooter's cheek between the 9 and 11 O'clock positions, so to speak, as well as not interfering with the right hand grip as much as the standard cheekrest did.
I could never get a proper grip on wrist of the butt on the T's I own(ed) with the the standard cheekrests as they prevent the ball of the thumb from getting over the top of the wrist, unless moved back so that the front of the rest was level with the heel of the wrist. Why they were placed so high up the wrist I've never been able to figure out. What do you think Peter?
The LB "Monte Carlo" stock was very well liked in the 1944 trials in the UK, so why it was not adopted is uknown; officially at least.
The greater comfort and control is obvious, particularly with the hard rubber butt pad. It seems everyone got to use one from target shooters to hunters, but the poor old snipers never did, outside Canada. SILE made tens of thousands of copies, as did others, so they were available all through the 50s and 60s from Parker Hale etc.
As it would have done away with cheekrest fitting and one part and two screws, it would have been a considerable simplification and savings in time. Would have been simplicity itself to provide a couple of spacer blocks to adjust stock length, or just keep a stock of butts of different lengths of course.
My $.02