A licence permitting an undertenant of commercial property to sub-underlet the whole or part of the property comprised in its lease. This licence is for use where the sub-underletting requires the consent of both the tenant and the landlord (the undertenant's landlord and superior landlord).

The underlease may be either an "old" or a "new" lease for the purposes of the Landlord and Tenant (Covenants) Act 1995. The sub-underlease will be a new lease for the purposes of that Act.

The document contains optional guarantee provisions for use where there is a tenant's guarantor, an undertenant's guarantor or a new guarantor for the sub-undertenant.