The FAs were specially trained to work on the Concorde, and apparently it was harder to qualify than for regular training. But it was a plum assignment, however the crews were rotated out (they would do a Concorde round-trip, and then short haul set of flights, then back to Concorde). I suppose this was to spread the work around and ensure a good supply of Concorde qualified crew, plus some incentive to do well on the Concorde. They really worked very hard, and it was some of the best service I've ever seen by cabin crew, both on the <20 pax flight (then they would typically have 8 crew) and on the oversold flights late in Concorde's life. But the change from sterling silver Concorde luggage tags to metal to plastic to paper was sad to see, sort of emblamatic of the progress of the airline industry and BA. On my last flight on Concorde, they were out of everything with a Concorde logo (and out of the caviar, as well as out of Pol Roger Sir Winston Churchill).