I must admit that it took me a little time to see it, but as you infer, it rather fits with the general appearance of the standards that applied within British Leyland at the time the MGB was in production. Indeed, the standards that continued long after - similarly there are errors and omissions within the factory manuals for the 200/25/ZR, including some information/procedures that are incorrect.
Maybe need to stare at the pic a bit longer and a bit harder. Once you have spotted it you will wonder how on earth you missed it at first
