(1) The general rule is that a claimant may discontinue all or part of a claim without the permission of the court.
(2) However —
(a) a claimant needs permission from the court to discontinue all or part of a claim in relation to which —
(i) any party has given an undertaking to the court, or
(ii) the court has granted an interim injunction;
(b) a claimant who has received an interim payment in relation to a claim (whether voluntarily or pursuant to an order under Part 17) may discontinue only if the —
(i) court gives permission, or
(ii) defendant who made the payment consents in writing;
(c) if there is more than one claimant, a claimant may not discontinue unless —
(i) every other claimant consents in writing, or
(ii) the court gives permission.
(3) If there is more than one defendant the claimant may discontinue all or part of the claim against all or any of the defendants.