156. Withdrawing or changing the terms of a Part 18 offer
(1) A Part 18 offer can only be withdrawn, or its terms changed, if the offeree has not previously served notice of acceptance.
(2) The offeror withdraws the offer or changes its terms by serving written notice of the withdrawal or change of terms on the offeree, and, subject to Rule 157, such notice takes effect when it is served on the offeree.
(3) Subject to paragraph (1), after the expiry of the relevant period the offeror may withdraw the offer or change its terms without the Court's permission or the offer may automatically be withdrawn in accordance with its terms.