“11 Assignments in breach of covenant or by operation of law. (1) This section provides for the operation of sections 5 to 10 in relation to assignments in breach of a covenant of a tenancy or assignments by operation of law (“excluded assignments”). (2) In the case of an excluded assignment subsection (2) or (3) of section 5— (a) shall not have the effect mentioned in that subsection in relation to the tenant as from that assignment, but (b) shall have that effect as from the next assignment (if any) of the premises assigned by him which is not an excluded assignment. (3) – (7) … ”
“25 Agreement void if it restricts operation of the Act. (1) Any agreement relating to a tenancy is void to the extent that— (a) it would apart from this section have effect to exclude, modify or otherwise frustrate the operation of any provision of this Act, or (b) it provides for— (i) the termination or surrender of the tenancy, or (ii) the imposition on the tenant of any penalty, disability or liability, in the event of the operation of any provision of this Act, or (2) it provides for any of the matters referred to in paragraph (b)(i) or (ii) and does so (whether expressly or otherwise) in connection with, or in consequence of, the operation of any provision of this Act. To the extent that an agreement relating to a tenancy constitutes a covenant (whether absolute or qualified) against the assignment, or parting with the possession, of the premises demised by the tenancy or any part of them— (a) the agreement is not void by virtue of subsection (1) by reason only of the fact that as such the covenant prohibits or restricts any such assignment or parting with possession; but (b) paragraph (a) above does not otherwise affect the operation of that subsection in relation to the agreement (and in particular does not preclude its application to the agreement to the extent that it purports to regulate the giving of, or the making of any application for, consent to any such assignment or parting with possession). (3) In accordance with section 16(1) nothing in this section applies to any agreement to the extent that it is an authorised guarantee agreement; but (without prejudice to the generality of subsection (1) above) an agreement is void to the extent that it is one falling within section 16(4)(a) or (b). (4) This section applies to an agreement relating to a tenancy whether or not the agreement is— (a) contained in the instrument creating the tenancy; or (b) made before the creation of the tenancy.” (a) it would apart from this section have effect to exclude, modify or otherwise frustrate the operation of any provision of this Act, or (b) it provides for— (i) the termination or surrender of the tenancy, or (ii) the imposition on the tenant of any penalty, disability or liability, in the event of the operation of any provision of this Act, or (a) the agreement is not void by virtue of subsection (1) by reason only of the fact that as such the covenant prohibits or restricts any such assignment or parting with possession; but (b) paragraph (a) above does not otherwise affect the operation of that subsection in relation to the agreement (and in particular does not preclude its application to the agreement to the extent that it purports to regulate the giving of, or the making of any application for, consent to any such assignment or parting with possession). (a) contained in the instrument creating the tenancy; or (b) made before the creation of the tenancy.”
“(a) by virtue of this Act a tenant is released from a tenant covenant of a tenancy, …”