Bats in the belfry, windows are jammed - London flat renting, deposits & landlords

Not to sub-let the premises or take in lodgers or paying guests without the prior written consent of the landlord. The consent will not unreasonably be witheld but it may be withdrawn on reasonable grounds and with the provision of reasonable notice.

Not to assign, in whole or part, the tenancy of the premises without the prior written consent of the landlord. Such consent will not unreasonably be witheld. The tenant will be liable for any reasonable expenses incurred by the landlord in arranging the assignment.

So from that I don't see that he can arbitrarily bump up the price of the rent. Or am I wrong?