Arguably (and to use a phrase I haven't on here for many a moon i.e Devil's advocate) concessions 'kick in' at the statutory retirement age when folk no longer recieve any remuneration for their efforts at work.
(I will at this point deliberately sidestep the fact that many people, through no fault of their own are no longer recieving such remuneration due to their status as one of Mr Duncan-Smith's feckless wasters)
So, presently the female concession is 60 and the male 65. This is of course due to change with ststutory retirement ages either increasing or ceasing to exist entirely.
And BTW there are concessions for students who have suitable evidence of their status (NUS Card, current, in date, Student photo ID etc)