Just to get the figures right, 20 flying Concordes were built (plus a couple of accelerated fatigue ground-rig airframes).
6 of these were pre-production machines (3 British, 3 French), and 14 were production Concordes that went into airline service (7 each for BA & AF).
AF lost 2 (Paris, and the one that was scrapped following the Dakar heavy landing). So 7 BA & 5 AF production Concordes have gone into preservation, plus the pre-production ones.
SSD