If I have understood him correctly, the suggestion is that if we discover that change of position is not available for a claim like Woolwich, then the unavailability of change of position throws into doubt the correctness of categorising the claim in Woolwich as lying in unjust enrichment.

I don't think that follows. Change of position is only available to answer claims for restitution of unjust enrichment. Lord Goff told us in Lipkin that the defence may not be available for all claims for restitution of unjust enrichment. If it were to turn out that change of position is not available in a Woolwich case, that does not itself mean that Woolwich has nothing to do with unjust enrichment. At best, we could only say that the unavailability of the defence is neutral as to the correct classification of the claim. We are still left with the question - on what principle is that claim based? It is perfectly rationale for the law to say that the claim arises in order to prevent unjust enrichment, but that for this particular claim the defence is not available. Similarly, change of position may not be available because the defendant acted dishonestly. The fact that defendant is liable to restore the wealth transferred to him by the plaintiff even though, at the time of action, the defendant is no longer enriched does not at all mean that the claim is not about enrichment.

Jonathon Moore
Christ Church College
Oxford