What is the liability of a solicitor to others than their client?

The seminal decision which gives rise to the liability of the solicitor to others than his or her client is Ross v. Caunters, [1980] Ch. 297. This decision involved a solicitor who prepared a will for a testator and sent it to him for execution but failed to warn him that the will should not be witnessed by the spouse of a beneficiary. One of the witnesses was the husband of the residuary beneficiary under it. After the testator's death it was determined that the gift to that beneficiary was void. Consequently, the beneficiary claimed damages against the solicitor for negligence in respect of the loss of benefits given to her by the will. The solicitors admitted that they had been negligent but contended that the only duty of care which they owed was to the deceased testator and that they owed no such duty to the beneficiary.