"The conclusion to be drawn from the trilogy of 19th century cases to which I have referred and the qualifications expressed in the modern case law is that communications between parties or their solicitors and third parties for the purpose of obtaining information or advice in connection with existing or contemplated litigation are privileged, but only when the following conditions are satisfied: (a) litigation must be in progress or in contemplation; (b) the communications must have been made for the sole or dominant purpose of conducting that litigation; (c) the litigation must be adversarial, not investigative or inquisitorial."