Herod has it, think they actually held up excavating the runway until the conditions were right to get the Concorde in. Seem to recall there are some pictures in or around the a/c itself. LDA is around 4500 feet now but was probably nearer 6000 before the rwy was shortened so I suppose not that dramatic in an empty a/c if dry and wind OK. Seen one land in that kind of distance on 14 at EGNM with a charter load.