Most are leasehold. Mine has no mortgage but as a leasehold I am restricted to allow others occupying it. It has 999y lease. Is it legal for the landlord to insist on who occupies, considering they only own the ground but not bricks etc?
If as you say you do not occupy the property but your son does, the freeholder may be worried that you are subletting and if there is a clause in the lease that does not permit this, s/he may be seeking to protect their interests. I suggest that you need to consult the lease to verify the terms and conditions. Land Registry should keep a copy. Alternatively, contact the advisory service that Buenchico suggested last month. https://clients.lease-advice.org/appointments.aspx
I'd have someone who knows about leaseholds have a read through the lease and the title generally, to check whether there is anything covering this. Also wort checking in case there is any separate Deed of Covenant in place which contains any restrictions.
Are you dealing with the Landlord directly, are they a company or individual and is there a Management Company in place or any managing agents involved?
Eve, a company & there is no individual landlord listed. Its a close of 20 maisonettes (10 semi detached houses divided into maisonettes) with mostly rentals.