Andrew Chadwick
I don't think these are a thing any more, now we're just letting COVID rip and pretending the pandemic is magically over. Certainly the RM "services near you" page doesn't describe it as such: https://www.royalmail.com/services-near-you#/results?postcode=OX29%206RA&latitude=51.811969&longitude=-1.441812&searchRadius=40&count=7&filters=&officeType=postboxes

The OSM node describes it as a post box, which is accurate https://www.openstreetmap.org/node/9334632617#map=19/51.81265/-1.44136&layers=N