Peter, I think the point that may have to be made when using Hedly Byrne v Heller & Ptns is that a special relationship must exist, but special relationship was not defined. Remember negligence in the sense of carelessness does not give rise to civil liability without there being a breach of duty of care, which has been defined. Most duties of care are the result of judicial decisions.
If you are interested have a look at: Doctor’s duty of care Bolum v Friern HMC 1957, which gave rise to the Bolum test & Road user’s duty of care: Nettleship v Weston 1971