Hi Robin - this is Marion, who started the post about Thomas Gaunt. Gaunt arrived in Melbourne in 1855/56 and started his business in 1859. Sometime about 1873 he employed Henry Vanheems, who became the manager of the Royal Arcade shop while Gaunt continued to run the business until his death in 1890. Vanheems was one of three executors of his estate; his will can be downloaded from the Public Records of Victoria (PROV) website.
I have recently published a book about Thomas Gaunt, "Gaunt's Time: Thomas Ambrose Gaunt, 1829-1890" - please PM me or respond via this thread if you'd like any further details. I'm happy to correspond with you and always happy to find out more about Thomas Gaunt!