In December 1947, the Koo Wee Rup Sun announced that the Grosby Shoe Co., P/L had purchased the Flax Mill buildings in Koo Wee Rup. They planned to specialize in the manufacture of slippers and open operations in early 1948. The Flax Mill had operated from December 1940 until November 1946, you can read about it here. As the article from the Koo Wee Rup Sun notes, Grosby also operated a factory at Beaconsfield, which had opened in May 1945 and operated until around 1953 (1).
There were various advertisements in the newspapers over the next few years for staff at the factory -
The Staff at the Grosby factory were featured in a Weekly Times special on Koo Wee Rup in July 1952.
Less than a month after the photo appeared in the Weekly Times, the Koo Wee Rup Sun on Wednesday, August 20, 1952 announced that the Grosby factory would be closing that day. The employees were redeployed to the North Melbourne factory. The building was auctioned on December 13, 1952. What happened to the building after Grosby left? As I wrote in my post on the Flax Mill, here, one building, an army hut, was erected on land adjoining St John's Catholic School in Koo Wee Rup, I don't know the date; and in 1964 the old amenities building was purchased and used as the Scout Hall. That's all I can tell you at the moment.
Footnotes
(1) Grosby factory at Beaconsfield - the building was owned by Herman Roberts and later Katherine Lucy Roberts, who both leased it to Grosby. The Shire of Berwick Rate books list Grosby as the tenant until 1953/1954. See Marianne Rocke's entries on these people here and here on her Residents of Upper Beaconsfield website.