A few more remarks about tank 5 (the one that was at the origin of the huge fuel leak).
First of all, for the moment, the theory that the tank was "full to the brim", with very little air space left, which led to the impact of a large piece of tyre provoking a shockwave in the fuel, knocking out part of the tank structure, is still the most likely one.
It's also one of the essential parts of the sequence of events that led to the crash, (unlike all the other details being dragged in, like the wind or the exact take-off weight).
It has been proved difficult, if not impossible, to reproduce the exact conditions during tests.... not that amazing really... but the huge piece of tyre and the panel punched out of the tank were there on the runway for all to see, even if the mechanism wasn't fully understood.
Second, as mentioned earlier, only tanks 1 to 4 had some fuel added during ground refuelling ; however (as somebody just reminded me), the flight engineer could use 'override' switches on the fuel control panel to top off tanks like tanks 5 and 8 to 'fine-tune' the tank contents and the CG during taxy, and probably did, so there is nothing very mysterious about tank 5 being "full to the brim" during take-off.
Third.... I think, in the context, "over-filling" is an unfortunate expression that has caused unnecessary confusion.
It evokes images of "over-doing it" or "over-eating".... something that maybe should not have been done.
In reality, maybe a term like "manual topping-up" would have been better.
The procedure is perfectly normal, without any danger in normal operation, and was used regularly.
It's exactly like your car at the petrol station... the petrol pump will cut out automatically when the tank is about 95% full. You can squeeze in a few more litres if you want to.
For your car it's just a matter of getting the pump to show a round figure in pounds (or euros), for Concorde it was a matter of adding the few hundred litres that would be burned during taxy.
So, on Concorde, there was nothing wrong with "topping up" tank 5 "to the brim", whether done during refuelling or by the F/E during taxying.
What nobody could have foreseen was that it would become one of the primary items on that ghastly day in July 2000....
CJ