A retail shop lease may contain a provision which allows the lessor to refuse in the lessor's absolute discretion--
(a) consent to the grant of a sublease, licence or concession in respect of the whole or any part of the shop, or
(b) consent to the lessee parting with possession of the whole or any part of the shop, or
(c) consent to the lessee mortgaging or otherwise charging or encumbering the lessee's estate or interest in the lease.