I have now found some information on the wooden building that was the
boys school before being demolished c1948 to make way for the "new"
building opened in 1950. Just for the record:

8 April 1886
Tenders invited for construction of a new wooden building in Brookes
Street nearest St Pauls Terrace to house the boys’ school. Closing
date 30 April 1886.

25 August 1886
Contract let to Leonard Silcock to build new boys’ school @ £2770.0s.
0d.

4 October 1886
Commissioner for Railways advises extension of railway from Brunswick
Street to Mayne will affect the FVSS and asks that building be
suspended. Some land that was originally school land was resumed for
railway purposes.