1887 was also the jubilee year for Victoria- major celebrations, hype, pomp etc.

The portraits show a marked change on coinage compared to the 'young' portrait in previous years, now crowned and bejeweled in full regalia where the previous portrait lacked all such accoutrements.

https://mjhughescoins.com/queen-victoria-gold-sovereigns-portraits-heads/ (see the first two in the row).

Interestingly, 'jubilee' looks to have a couple of meanings:

a special anniversary of an event, especially one celebrating twenty-five or fifty years of a reign or activity.

JUDAISM a year of emancipation and restoration, kept every fifty years.

It seems that 2. could be of significance to the developments of the era- through 'their' eyes it was likely viewed as emancipation.

Possible major moves made within the significance of that particular year.

Nice work by the way- as always.