In the typical professional liability claim, the claimant will be a former client. It will likely be common ground that the professional owed a coterminous duty in contract and at common law. The battleground will be over matters such as the scope of the duty, whether it was breached and whether any breach caused a loss. Less commonly, the claimant may be a third party which insists that, in carrying out services for its client, the professional also assumed a responsibility to that third party. The note can be accessed here.