Legislation: Companies Act 2006
Leaseholders can have two related, but separate legal relationships - one as a tenant/leaseholder under the lease, and another as a member or shareholder of a company A “Resident's Managing Company” (RMC) or “Right to Manage Company” (RTM) which is responsible for the management of the development, appointing a managing agent, enforcing the terms of the lease etc.
In many modern leases, if there is an RMC, it will be named on the lease (and possibly along with the freeholder or other landlords), and hold the head lease for all of the development with rights and responsibilities to assign them when flats are bought and sold. The RMC as the landlord can also bring forfeiture proceedings against a leaseholder if they have breached the lease or not paid the service charges etc. (An RTM company can't do this bit.)