AHC: Return Annobón to Portugal

[Iserlohn]

Spanish Guinea, today known as Equatorial Guinea, always struck me as odd but personally the oddest thing about it is Annobón. That small island barely south of the equator is 1) culturally and geologically quite similar to nearby São Tomé and Principé and 2) according to Wikipedia Spain actually had major difficulties asserting control over it.

Now based on those two statements I wondered... How and when could Annobón be returned to Portugal, with a POD between 1815 (so that you can't use the Congress of Vienna as an excuse) and 1900? Bonus points if Spain keeps the remainder of modern Equatorial Guinea (aka no Spanish collapse).

 

[Archangel]

Spanish Guinea, today known as Equatorial Guinea, always struck me as odd but personally the oddest thing about it is Annobón. That small island barely south of the equator is 1) culturally and geologically quite similar to nearby São Tomé and Principé and 2) according to Wikipedia Spain actually had major difficulties asserting control over it.

Now based on those two statements I wondered... How and when could Annobón be returned to Portugal, with a POD between 1815 (so that you can't use the Congress of Vienna as an excuse) and 1900? Bonus points if Spain keeps the remainder of modern Equatorial Guinea (aka no Spanish collapse).

One possibility is that Portugal finds some good source of revenue in the colonies and tries to buy back Annobón for internal politics, or that a complex diplomatic trade is made, with Spain returning Annobón in return for support in some conflict or arbitration.