Recourse to the online Argus has revealed that the M&MTB Roll of Honour was unveiled in 1921, as below:
TRAMWAYS HONOUR ROLL.
Unveiled by the Premier.
The Premier (Mr. Lawson) unveiled yesterday
the board at the offices of the Melbourne and
Metropolitan Tramway Board erected in honour
of 518 tramway men who enlisted, 71 of whom
fell on service abroad, and 18 of whom received
awards for conspicuous gallantry.
The board is of artistic design in black-
wood, and is erected on the main stair
way to the administrative offices.
It was designed by Mr. H. B. Herbert
In the presence of members of the board
and officers of the administrative staff, Mr.
Lawson unveiled the memorial. The
record of their services, he said, showed
that tram waymen, who spent their lives
in giving public service, had done valiantly in ren-
dering the greatest of all services on foreign fields.
The memorial would stand for all time to remind
us that only by living up to the ideals for which
these brave men died could we achieve the fruits
of the victory they had won. Germany had lost
the war, but stood to win the subsequent eco-
nomic conflict if we by our indifference and
neglect, and our division into sects and factions,
failed to remain steadfast to those ideals of
courage, loyalty, and truth.
The Argus 9 November 1921
See the board referred to here.
It seems likely that H B Herbert was the Melbourne artist Harold Brocklebank Herbert. The MMTB offices in 1921 were at 673 Bourke St (south side) between Godfrey and King Street. (Thanks to Jenny Coates for her kind assistance.)