DH is 4 years younger than me but does a very physical job (building trade) and I think that he will want to retire round about the same time as me.
However I don't think "age" necessarily the prime factor when it comes to retirement, life has a habit of throwing up the unexpected at you as you get older, think of all the health issues that have a habit of arising, and existing conditions that get suddenly get worse as you push yourself to cope with a busy lifestyle as you approach your sixties!
There is also the financial aspect around this, what you were advised would provide a good pension in your 40's can prove to be inadequate 20 years on.
This has certainly happened to us! instead of DH paying into all these pension funds since he was 17 ,( he would have been better off putting all the contributions under the mattress or in the Bank)
I know plenty of people who have planned to retire at a specific time only when they get there they change their mind for one reason or another.
I think the OP should just say "Yes dear" when her DH talks about retirement the reality in the future could be very different.
In short I think it is something in this day and age that you cannot have plans set in stone...(.Mr Cameron please take note).....Unfortunately our politicians are far too young to have any idea how hard commuting, working, having older children still living at home, in your sixties is!