A sublease is a lease granted by an existing tenant (the sub‑landlord) out of its own leasehold interest to a sub‑tenant, for all or part of the premises, for a term shorter than the tenant’s own lease. It does not usually create a direct contractual or proprietary relationship between the landlord and the sub‑tenant; the tenant remains liable to the landlord under the headlease and typically retains control over enforcement against the sub‑tenant.In practice, subletting is commonly used for surplus space, group reorganisation or occupational flexibility. Whether a tenant may grant a sublease, and on what terms, is governed primarily by the alienation provisions in the headlease and, in England and Wales and Northern Ireland, by statutory controls such as the Landlord and Tenant Act 1927 and Landlord and Tenant (Covenants) Act 1995. Similar principles apply in Scotland and Ireland, although detailed statutory regimes and terminology (e.g. sub‑tenancy, sub‑underlease) may differ.Key legal issues include landlord’s consent, rent levels, term, rent review structure, compliance with use and alterations covenants, registration and securities over the sublease, and ensuring the sublease is contracted out of, or benefits from, statutory security of tenure where relevant.