This letterbox hybrid cache is not at the posted coordinates, but this is a good place to park and start your adventure.
Caixa de correio is the Portuguese term for letterbox. Welcome to this new series of London Letterbox caches honouring many different countries and languages around the world. This cache contains a stamp that is not a trade item and should remain with the cache.
From the listed coordinates, you will be hiking east across a grassy field. You can find the final cache coordinates by projecting a waypoint 96 m away, at 105 degrees true.