And this is the problem with no state-issued ID/resident’s permit cards in the UK.
I can totally see why OP doesn’t want a plastic driving licence. I have an old paper one, but that’s because Belgium is even more backwards than the UK and only started issuing plastic driving licences around 10 years ago.
Anyway, Belgium issues state ID cards for citizens and resident permit cards to foreigners. Not valid ID for travelling abroad, but you can’t pick up registered packages without it.
Not sure why the whole ID card debate got everyone in a fluster a few years ago, but for people who cannot drive and have never been abroad, it must be frustrating not to have picture ID.
UK passports are also hideously expensive and bulky. I think mine cost around £150 as it had to be shipped from France as the FCO no longer issue passport in Brussels....