Was it Mann's electrical? I would have placed them on the north side of the street, opposite the Acme/Tilly/EWB factory, but it was a long time ago...
R - E.W. Brown were motorcycle manufacturers, and later moved into motor cars. The petrol tanks were made by Edwards Bros, in Richmond, and were stamped E.B. There was an E.B. motorcycle, but it was made by A.G. Healing, and not E.W.B., which would have been more fun! My head is exploding with Australian motorcycle info, ordered by letter.
Here's Duigan's airplane, the engine of which was built by J.E.Tilly in the old factory. In July 1910 it made a "hop" of 24 feet, but it was deemed that the original engine was not powerful enough for sustained flight. Tilly built larger bore cylinders and water-cooled cylinder heads, and with this new engine Duigan flew later in 1910. The original cylinders and heads presumably went under the bench in Little Latrobe Street, and employees Bob King and Reggie Robertson fancied they could build a motorcycle engine using them. So the four heads and cylinders went to build four Lennox motorcycles at King's new works in Lennox St, Richmond. "L is for Lennox"!
Leon