Hi,
I am looking for some credible evidence on whether AFD systems are maintained by occupants of private residences. Installing them is a Building Regs requirement, but maintaining them appears not to be. Has anyone produced any research on this?

If you are asking are interconnected smoke alarms that are required by building control maintained by the house owner the answer has to be 99% do not bother.

I for one have seen countless smoke detectors that are either open (so you can see there is no battery) or the battery compartment is pulled out.

Let me ask this, how would you "police" such a law?

You could start with the annual fire statistics 2011/12 (the latest) at https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/36467/FSGB_2011_to_12.pdf and go to page 34 and check out Smoke alarm analysis (Tables 2.3 to 2.9 and Figure 2.3). Try http://www.civil.canterbury.ac.nz/fire/pdfreports/Duncan.PDF is a New Zealand document but may be worth a read, there are British reports as well and I will see if I can locate them.