them, or whether to take the unauthorised investment as part of the trust fund. This is considered the exception, rather than the rule; in Foskett v McKeown, Millett said that "The primary rule in regard to a mixed fund, therefore, is that gains and losses are borne by the contributors rateably. The beneficiary's right to elect instead to enforce a lien to obtain repayment is an exception to the primary rule, exercisable where the fund is deficient and the claim is made against the wrongdoer and those claiming through him". Innocent parties and mistake Where funds are mixed with those of another trust, or mixed with the funds of an "innocent volunteer", certain general principles apply. As laid out in Re Diplock, the principle applied is that the claimant's entitlement ranks pari passu to that of the volunteer; each has an equal claim to their funds. Whether the fund decreases or increases in value, each party can claim a percentage equal to their contribution. The problem here comes if the mixed funds are used in unequal chunks to acquire other property. The long-standing rule is that established in Clayton's Case; that the money deposited first is deemed to be spent on the first property purchased. The problem with this is that if the first property becomes less valuable than the second property purchased, the first claimant loses some of their money while the second claimant is able to claim their money in its entirety. The alternate approach is the previously mentioned pari passu idea; whatever the total property is worth, the claimants get a share proportionate to their input, without assuming that the first claimant's money is tied to the first property purchased and the second claimant's money to the second property. In Barlow Clowes International v Vaughan, the Court of Appeal applied a similar set of principles, holding that the size of the contribution and the amount of time the money was part of the mixed fund were the factors to be considered. Where payments have been made by mistake claimants may or may not be able to recoup their losses. The leading case is Westdeutsche Landesbank Girozentrale v Islington LBC, where Lord Browne-Wilkinson declared that a constructive trust would be created when the recipient of the funds became aware of the mistaken transfer. As such, ignorance of the mistake would not create a fiduciary relationship, therefore not a