That's basically it, Davef68. It's the difference between sections 1(a)(i) and 1(b) in the current legislation, i.e. the
Fatal Accidents and Sudden Deaths Inquiry (Scotland) Act 1976, my bold:
1 Investigation of death and application for public inquiry.
(1)Subject to the provisions of any enactment specified in Schedule 1 to this Act and subsection (2) below, where—
(a)in the case of a death to which this paragraph applies—
(i)it appears that the death has resulted from an accident occurring in Scotland while the person who has died, being an employee, was in the course of his employment or, being an employer or self-employed person, was engaged in his occupation as such; or
(ii)the person who has died was, at the time of his death, in legal custody; or
(b)it appears to the Lord Advocate to be expedient in the public interest in the case of a death to which this paragraph applies that an inquiry under this Act should be held into the circumstances of the death on the ground that it was sudden, suspicious or unexplained, or has occurred in circumstances such as to give rise to serious public concern,
the procurator fiscal for the district with which the circumstances of the death appear to be most closely connected shall investigate those circumstances and apply to the sheriff for the holding of an inquiry under this Act into those circumstances.