The "sleeping accomodation guide" issued by HM Government would state that if the buildings were built to current building regs then AFD in the common parts would not be required.
If you do have true 60 minute separation / compartmentation and the common areas are completely sterile then i would ordinarily say that a common fire alarm system is not be required.
That said however the fire risk assessment should determine the standards required, and without seeing the premises it is hard to comment on whether it would be a definative "no AFD is not required" or otherwise.
There is legislation that covers the common areas of flats - it would be the Regulatory Reform (Fire Safety Order) 2005.
Again it is down to risk assessment, if a resident has gone on holiday and left a fan heater on, and it causes a blaze at 3 in the morning will anyone be able to detect it before it breaches the 60 minute fire resistance?
I know of some fire safety professionals who would say that they have never heard or come across a blaze in a 60 minute compartment which has gone undetected and affected other residents (even in the small hours of the night) The reasoning they give is that someone somewhere will always see it and call for help.
Look at your occupants / residents - are they vulnerable people (i.e; elderly, less abled etc).
Some fire safety professionals will say that you are able to accept window escape in anything less than 4.5 meteres in height , not something I personally are keen on, but converseley its not to say it is wrong, plus it does give people an alternative if the main escape has been compromised or they cant reach it for whatever reason .
It probably doesn't answer your question unfortunately but hopefully it will give you a bit more to think about to help you arrive at the appropriate plan of action. It all comes down to that magic term " risk assessment ".