27. Nothing in paragraph 20 or 26 shall preclude Merseytravel from submitting at any time, or from time to time, but in no case less than 28 days before commencing the construction of any specified work, a new plan thereof in lieu of the plan previously submitted, and thereupon the provisions of those paragraphs shall apply to, and in respect of, such new plan save that the reference in paragraph 26 to 42 days shall be treated as a reference to 21 days.