"in the two cited cases, these weren't Brits, just natives who were being subjugated by them"

Pitcairn Island is inhabited by the descendants of the Bounty mutineers and the Tahitian natives who accompanied them.

During the 1793 conflict on Pitcairn, five of the British mutineers were killed. And in the aftermath the remaining Tahitian men were killed. After this two of the four British sailors took the lead.

Although the culture has some blending with Tahitian influences. Ferinstance, the language of the island is an English creole: Pitkern.

Pitcairn once had an indigenous* polynesian population. But it collapsed and went extinct a couple of centuries prior to its "discovery" by Europeans. ( * Well, everyone is an immigrant or colonist somewhere from somewhere else. The polynesians have their roots in SE Asia. )

St. Helena was also uninhabited when the Portuguese stumbled upon it. Despite some exploitation of the island, peopling it didn't happen until the British East India Company decided to have planters settle there.

So both cases are of British subjects practicing their values in near isolation from Blighty.

Dante