I did PO digital check and send too, apparently it went to Durham, but as you say there is no way to track your passport since it is sent in a special pouch, or so I have been told. I thought that I would speed things up by using post office for photos etc. but it seems that this is not the case. My passport is still not registered as received and post office staff say that there is no way to confirm that the pouch with my passport has even reached the Passport Office!
