On the Facebook group Bygone Bedlington a member, Ian Foster, posted this clip from the BBC archives when the BBC was looking for the 'Market Place' Post office and you will need the volume turned up to listen to this :-
https://bbcrewind.co.uk/asset/611257809e2c440020e8f292?selectedLatLng=55.13239860534668%2C-1.5979957580566406&zoom=11
So I checked the journey of the Post Office
When it was in the Market Place :-
Then it moved to 40 front Street East and was still called the Market Place Post Office :-
Where it is now - Google Street View 2024 - 20 Front Street