The supersonic Victor question has been discussed here quite recently. Somebody pointed out that the machmeter was known to be inaccurate, and an indicated mach 1 might not necessarily be correct. Whatever the truth, you only have to look at a Victor (particularly a B1 before they started sticking bits on it), to see that was a very "slippery" aircraft, and mach 1 in a shallow dive was quite credible.