Before simulators got good enough the training was indeed done on actual aircraft - as some still do.
Concorde must have had a simulator but live training was also performed in circuits (patterns to our US cousins) throughout its service life, generally at Shannon.
There had been a steady attrition of aircraft over the years, well into the jet era, of aircraft on type conversion training being lost in engine failure/go-around scenarios and similar, when the trainee lost it and the check crew didn't grab the situation in time.