I have no reason to doubt your word, as regards Manchester &, perhaps, elsewhere. I began at LATCC in 1971 & AF were using flight numbers then. But, I know that the info. I have already posted is correct, as regards the trans Atlantic flyovers in the C.Is area. Another flight number used, in the '60s, was AF707 & the returning 077 came back as the 070.
I think that, as already stated, AF used regs. on flights operated elsewhere in the '60s (as for the LFPO to LFRB flights - we certainly "copped" VC7s flying south of our area from the r/t c/s - a registration).
Does anyone else have any info?