Pretty much every small speck of land in the Pacific was claimed under the
Guano Islands Act. Many of these claims fell dormant relatively quickly, but some endured until very late (often only being repudiated by treaties with the newly independent states in the late 20th Century). I won't bother replicating the full list, but some notable examples:
-The Line Islands (Kiribati): subject to a continual US claim from the late 19th Century to the Treaty of Tarawa in 1979.
-The Phoenix Islands (Kiribati): Claimed in the 1930s for air bases and repudiated at Tarawa
- The Northern Cook Islands: Claimed in the late 19th Century and not repudiated until the 1980 border demarcation
-Tokelau: Claimed at some point in the 19th Century, repudiated in 1980 with the Treaty of Tokehaga.
All of these are good candidates for being bartered by Britain in exchange for something else (abandoning US claims to some Caribbean Islands or getting their favour in a diplomatic situation), or particularly in the case of the Phoenix Islands could be sold to the US as part of the finances for WWII if things went differently.