Paragraph 16 No liability for landlord and tenantI1

to maintain, repair, replace or insure any item of fixed equipment which the landlord and the tenant agree in writing to be obsolete or redundant to the farming of the holding;

to maintain, repair, replace or insure any item of fixed equipment which, in the event of any dispute between the landlord and tenant as to whether it is, or before being damaged or destroyed by fire was, redundant to the farming of the holding, is awarded or determined to be redundant by an arbitrator or third party under paragraph 15; or

to execute any work if and so far as the execution of such work is rendered impossible (except at prohibitive or unreasonable expense) by reason of subsidence of any land or the blocking of outfalls which are not under the control of either the landlord or tenant.