Theman76 what do you mean when you say "you saw nothing there"? How did you survey the area?

The definitive source would be Royal Mail, and their website states there is Post Box there. Also confirmed by Google Streetview. We MUST NOT use either of those sources as a source for adding the Post Box, but they confirm a Post Box is present.

Sources we can use are Post Hoc
https://osm.mathmos.net/postboxes/box-info/?ref=DT6+13
This confirms a post box was present,
We can also check sites like wikimedia commons, which has a picture of the post box
https://commons.wikimedia.org/wiki/File:Monkton_Wyld,_postbox_%E2%84%96_DT6_13_-_geograph.org.uk_-_2259282.jpg

So we can use this note + Post Hoc + wikimedia image to add the post box.