These were bought 20 years ago and hardly used.   Probably no more than an hour's use.  Just not needed to use.  Certainly not due to any issues with them.

They came with an A4 sized certificate from British Airways but unfortunately I cannot find it.  I am pretty certain I won't have got rid of it (I live in the same house as when bought them).  If I ever find it, I would promise to send it to the buyer if they are bought before I find it.

These are from a smoke-free home.

Sent via First Class recorded delivery within 24 hours (or on Monday morning if ordered during a weekend).

These are some of the comments I've read about them on the internet for help with this listing:

"Technically the most expensive headphones I will ever own as they were only given away with a £10000 ticket on Concorde!! Initial first impressions are very very positive. I've got a pair of HD25 SP2 and absolutely love them but these are a step above. The bass feels cleaner and the treble isn't quite as shrill. The sound is altogether cleaner and more precise. It's not a great song but I like to demo phones with Bang Bang by Jessie J because it has good bass with a range of female vocals. On the Concordes there is more of a separation between the bass and vocals. On the SP2s they're a bit more muddied together. Not bad just not as good. The Concordes basically sound like eq'd SP2s out of the box."

"As I understand it, HD25's were well established professional headphones before British Airways started using them on Concorde. The Concorde headphones were modified from the standard HD25's to increase their impedance to 300 ohms and the headband was the simplified design similar to that used on the classic HD414 and its successors."