I got an email from the Post Office today, they ….
“confirmed that the box is in use and is cleared twice a day at 11:30 and 18:30.
they go on to say
“Please rest assured that a new plate detailing collection times has been ordered for the post box and the Christmas sticker has been removed. …… it has been emptied on a regular basis and is fully operational.
So all those times we walked past, we needn’t have!”               Now we know!