This box diagram dates from 1964 at which time 3 position signals were introduced from Westgarth to Alphington. At this time the up distant was abolished, replaced by an automatic signal.
The short single line section from Clifton Hill to Westgarth saw several safeworking systems over the years:
Large electric staff, 1912 - 1916
Miniature electric staff, 1916 - 1926
Lever Locking & Track Control, 1926 - 1968
In 1968 the interlocked gates were replaced by booms and the all signals and points were controlled by Clifton Hill B box which itself is no more as the whole area is now controlled by Metrol.
diagram courtesy David Campbell