I remember having a BA Exec Club "Charge Card" in 1989ish.

I could walk up to a ticket machine, stick the card in, and get a ticket/boarding pass for the next Shuttle to MAN or LHR. If the flight was full, they'd add another flight (even if it meant it was Concorde).

At the end of the month, I'd get a bill which detailed all the flights.

I *think* it was a set fare for the flight. Maybe 54 quid each way?