once upon a time, you worked til you dropped.
I recall on joining the computer lab, seeing Roger Needham, Karen Spärck Jones, Robin Milner, Maurice Wilkes, David Wheeler, Mike Gordon, on pretty much a daily basis - just to say, to get shouted at by Karen for carrying my bike in to my office, to work on grand challenges for CS for the UK with Robin (and comment on his bigraph work) to hear David Wheeler's amazing cutting insights into the most basic algorithmic ideas, to see where Mike's work on formally verified processors might go next, to be told off by Maurice for even thinking of building an affordable all optical processor (he cited Grace Hopper's "here's how big a photon is")...
They have all passed on now, sad to say, some before their time. But they were in the lab, as likely as not, til the day before...
Since then, the University has seen fit to operate a less enlightened ageist approach to retirement currently under review, which is pretty ill thought out, in my humble opinion.
The Doors said Noone gets out of here alive, but the university seems to think differently.
One of the most bogus arguments used for Employer "Justified" Retirement Age is that of "succession". When I was an undergraduate, there were still colleges that did not admit women. One of their arguments was that if they did, they would be excluding some smart young men.
The point was that as soon as one is gender-blind on admissions, one realises that the purpose is including people based on their ability to take advantage of, and/or contribute to the role, not on some arbitrary attribute (like having red hair or being a zoroastrian).
The idea that not allowing people to work past a "certain age" because that might not allow one to employ young people is a variant (albeit the other side of the equation, on exit, rather than entry) - if there is a shortage of "permanent" positions in the institition, then by all means make a comparison based on contributions. Basing it on some random chance factor (in the case of retirement, date of birth, rather than, say, gender) is bogus. (I wonder what those college people would have made of trans applicants too...). Given most people are a net asset to the university, even the "competitive" argument is pretty much nonsense too.