Had just a single flight on Concord...JFK > LHR in, I think 1983 or might have been 1984, after my BA flight that Saturday morning went tech and to my huge surprise, the BA desk gave me a ticket on the departing Concorde instead of the hotel voucher I was expecting....
Was even invited for a flightdeck visit after my ID fell out of my jacket pocket as I handed it to the c/c prior to departure....
My two memories are that as I entered into the flightdeck, we were about Mach 1.8 and FL 550 (!!) and I was greeted by the skipper, a Capt McMahon, who was sprawled low-down in his seat, shoeless feet on top of the instrument panel, smoking a Lucky Strike and doing a crossword....Being at the time a newly type rated F27 F/O and without even a decent A/P to help the day's work go by a little less tiringly, I remember feeling a huge sense of amazement that the crew were actually unoccupied at Mach 1.8 and FL 550....
The other memory is that the F/E's instrument panel had a gap of about 15 > 25 cms between the right hand edge and the adjacent trim panel....When I jokingly asked whether he ever dropped his pen / charts / clipboard holder into the gap, he replied that the gap 'appeared' in the cruise, due to heating and then expansion of the aircraft's airframe, and then closed up again as speed dropped back below Mach 1....He said that it was typical of an F/E's life that the only design fault on Concord directly affected the F/E !!
About 30 minutes before landing at Heathrow, the c/c came round offering all the pax a small souvenir - a gold plated note holder in a velvet presentation box both with famous 'C' logo engraved on them.....Although by then I'd already followed the example of the guy sat next to me and enjoyed several good quality ports before slipping the empty crystal-cut glasses, again with the inscribed 'C' logo, into my cabin bag as a souvenir....
Still use the glasses from time to time, but haven't a clue where the note holder is these days....