57. Where in consequence of the proposed construction of any of the authorised development, the undertaker or Northern Powergrid requires the removal of apparatus under paragraph 51 or otherwise or Northern Powergrid makes requirements for the protection or alteration of apparatus under paragraph 53, the undertaker shall use its reasonable endeavours to co-ordinate the execution of the works in the interests of safety and the need to ensure the safe and efficient operation of Northern Powergrid’s undertaking taking into account the undertaker’s desire for the efficient and economic execution of the authorised development and the undertaker and Northern Powergrid shall use reasonable endeavours to co-operate with each other for those purposes.