It is not just clients who may be able to bring a claim in negligence against their professional advisers. This Practice Note considers who can be parties to a professional negligence claim, ie who can bring a professional negligence claim: be it client, third parties and even, occasionally, those acting ‘on the other side’ of a transaction, and against whom such a professional negligence claim can be brought, with reference to when a professional owes a duty of care and to whom their duty is owed. For guidance on founding the duty on which the action may be based (and so where the issues can overlap with the identity of the parties as establishing a basis of claim), see Practice Note: Bringing a professional negligence claim based on the duty in contract, tort and equity. Professional owes a duty to their client—relevance of any retainer In most cases the professional owes a duty only to their client, in a strict sense. Who the client is will usually be apparent from the terms