Hopefully this may be of use to someone . . .
Other half did postal application (no idea why!) for adult renewal in mid May. Think the pre-addressed envelope had the Durham office on it.
Anyway the cheque was cashed on May 13th.
Received letter to say things were taking longer than usual on the 30 May.
Heard nothing more so getting panicky she tweeted them on the 12th June to ask how she could check the progress as she hadn’t written the number from the form down when she sent it.
Twitter reply told her to contact the Liverpool office via email which she did. And in this message she said she was getting worried as she needed the passport imminently.
They didn’t respond, however 2 days later she received another letter same as the first one (from an address in Southampton) telling her that things were taking longer than usual.
The following day (17th June) her passport arrived.
Don’t know if the chase up made a difference but it’s quite a coincidence if it didn’t!