57.—(1) Subject to Part 6, and to paragraphs 44(8), 45(9), 58, 59 and 72, a variation of, or amendment to, a contract is not effective unless it is made in writing and signed by or on behalf of the Board and the contractor.
(2) The Board may vary a contract without the contactor's consent where—
(a)it is reasonably satisfied that the variation is necessary in order to comply with the Act, any regulations made under or by virtue of the Act or any direction given by the Secretary of State under or by virtue of the Act; and
(b)it gives notice in writing to the contractor of the wording of the proposed variation and the date on which that variation is to take effect.
(3) The date on which the proposed variation referred to in sub-paragraph (2)(b) is to take effect must, unless it is not reasonably practicable, be a date which falls at least 14 days after the date on which notice under that sub-paragraph is given to the contractor.