20–21 June 1887 marked fifty years since Victoria took the throne (20 June 1837). London threw the pageant; Sydney kept empire time. The town treated the Jubilee as a public holiday pair — illuminations, loyal addresses, sports, school marches, and a flood of commemorative medals. At the Sydney Mint, Jubilee-head sovereigns and half-sovereigns began striking on 18 June 1887, with the Governor and Lady Carrington present for the first piece (Sydney Morning Herald, 23 June 1887).
This is not the 1897 Diamond Jubilee, and it is not the excuse for the Queen Victoria Building (that naming belongs to the later jubilee). Keep 1887 as golden — processions and coin dies — and leave the Market Street Romanesque pile for 1897–98.