In carrying out the authorised development the undertaker must construct any such work within the lateral limits of deviation or extents of work shown on the works plans for the relevant work.

In carrying out any work comprised in the authorised development the undertaker may deviate vertically from the levels of the authorised development shown on the engineering drawings and sections, to a maximum of 1 metre upwards or 1 metre downwards except that these maximum limits of vertical deviation do not apply where it is demonstrated by the undertaker to the Secretary of State’s satisfaction and the Secretary of State, following consultation with the relevant planning authority, certifies accordingly that a deviation in excess of these limits would not give rise to any materially new or materially different environmental effects in comparison with those reported in the environmental statement.