So - as I understand it - you own a leasehold flat or maisonette and your landlord (i.e. the freeholder to whom you pay ground rent) is demanding to be told who is living in your flat.
If that is correct, then you need to study your lease carefully to see what terms in the lease give the freeholder the right to demand the information. If there are none, ask the freeholder to tell you what gives him/her the right to have the information.
// gives him/her the right to have the information.//
er the right to demand the information from you
( I imagine but that is his affair - that it is in the public domain anyway - electoral roll and so on ) - so far you havent told us he is telling who can and cant live there
There is a Government-funded advisory service which can provide free information about leasehold matters over the phone. (You need to book an appointment online and then call them at the appropriate time but you get 15 minutes of professional advice for free, so it would seem worth doing):
https://clients.lease-advice.org/appointments.aspx
Whoever I accept to occupy/rent the m’ette is surely my business. I do pay the freeholder ground rent & ins. The only restrictions on Lease is building extensions.