Peter,

>It seems like this is very much comparable to the situation of the
>Congo in the 19th century, before it became a Belgian colony.

This was actually a fairly common arrangement in the early days of
colonialism. The British territories in North American were held by the
London Virginia Company, the Plymouth Virginia Company and the Hudson Bay
Company under charter from the English (and subsequently British) Crown.
Similarly, India and many other parts of the Far East were held by the East
India Company. It was only (much) later that they were formally annexed
into the British Empire.

I believe a similar arrangement existed with the Dutch VOC company in the
East Indies, and the Danish in what is now the US Virgin Islands. I also
seem to remember reading that the now largely forgotten Swedish West Indies
colony on Saint Barthelemy (now part of Guadeloupe) was effectively the
personal property of the Swedish monarch.

Regards,

Kevin Meynell