24 Because the first defendants' covenant to perform a fit out of the premises in accordance with plans to be submitted to the lessor for approval, it is necessary to examine the provisions of the lease which relate to alterations to any part of the demised premises and alterations to the electrical systems and installations. Sub-clause 6.2(a) of the lease contains a general prohibition against the lessee making, or suffering, any alteration or any structural alterations to be made to the leased premises and prohibiting cutting, maiming or injuring of any of the principal structure or walls or any part of them without the prior written consent of the lessor. Similarly, sub-cl 6.2(b) contains a prohibition against the lessees making any alterations or additions to any plant, equipment, fixtures or fittings forming any part of the building or the leased premises (including the air-conditioning plant, electrical fittings, plumbing and fire warning or prevention system) without the consent in writing of the lessor first being obtained. This sub-clause also provides that where it is necessary or desirable for alterations or additions to be made the work may only be done under the supervision of the lessor's architect and any other architects or consultants approved by the lessor. Sub-clause 6.2(c) forbids the lessees, without the prior consent in writing of the lessor, to install any electrical equipment in the leased premises which overloads the cables, switchboards or sub-boards through which electricity is conveyed, provided that if any consent to necessary alterations is required that electrical work shall be effected by the lessor at the expense of the lessees. Similarly, there is a prohibition set out in cl 6.2(e) against the lessees making any alterations or additions to any partitions within the leased premises without the prior written consent of the lessor, which shall not be unreasonably withheld. This covenant also provides that any application for consent for the erection, alteration or additions to any partitions should be made by the lessor in writing and be accompanied by detailed plans and specifications and, if approved by the lessor, should be constructed under the supervision of the lessor's architects.