A couple of points on some of the latest entries
Discharge valves
We definately used alternating systems outbound and inbound and only No 1 system had thrust recuperators. I think the original idea was that No 1 system would be used always with No 2 sytem being a back up. However from the start BA operated as I said alternating per sector so as to be sure that both system were working. The same logic went for the engine starting ignitors which were used Lh or Rh per sector. This logic caused more problems with starting than any other although a way was found to over come this problem
under wing
Not sure if I am on the same thread as others but there were definately strengthening straps / doublers fitted on the underside of the wing outboard of the engines, which were on a wing root/wing tip alignment. This surprised everybody as they seemed to go against all the need for limiting drag that had been impressed on us during the lectures.
These strengthening straps were fitted a few years after the start of service due to small cracks appearing in the outer wing, and only seen on BA aircraft. This was put down to the fact that in the early years BA Concordes flew heavy and subsonic for extended periods across Europe, on their route to Bahrain, whereas Air France aircraft always accelerated shortly after take off
Also either side of the engines there were two tubes on the underwing which went fore /aft. These tubes were the drain outlet for their respective engine dry bay and directed any fluid to the trailing edge of the wing.
Mind you all this is some 30 years ago so the old grey matter could be playing me tricks