The situation is different where an innocent volunteer spends the claimant’s money on an asset which he already owns.
In cases where no value is added to the asset, the claimant’s money is treated as dissipated and cannot be traced. In Re Diplock the court gave the example of an innocent volunteer who spent trust money in altering his house to his personal needs without adding one penny to its value.
In cases where value is added to the asset, Lord Browne-Wilkinson said obiter in Foskett v McKeown that the trust would not be entitled to a proportion of the value of the asset but ‘at most a proprietary lien’ over the asset. Furthermore the innocent volunteer may have a defence to the claim if it would be inequitable to enforce it