(1)The local authority may vary a maintenance plan in such manner as it thinks fit—
(a)if satisfied at any time that there has been a change in circumstances which justifies such a variation, or
(b)before doing anything under section 49 in relation to the plan.
(2)The local authority may vary a maintenance plan on the application of an owner of any of the houses concerned or of its own accord.
(3)The local authority may revoke a maintenance plan if it is satisfied at any time—
(a)that implementation of the plan is no longer practicable, and
(b)that the plan cannot be varied so as to make implementation practicable.
(4)The local authority must serve notice of any variation or revocation in accordance with section 62.
(5)Where a maintenance plan is varied, a copy of the revised plan must be attached to that notice.