Also just curious on the British Citizen passports applied from within the UK - on a normal renewal, are no paper submissions required?

If a paper submission is required, I far rather sign on the form, and have the signature pre-printed on my passport. I'm far less likely to sign badly, or forget about signing.

This has happened on my Australian psssports for as long as I had them. Of course, unlike British Citizen passports, Australian passports applications must be submitted at passport offices, post offices or diplomatic missions.

Signatures on my HKSAR passports are optional. There's a signature block on the last page, but underneath emergency contact information so it's not sure whether it's an official part of the passport or not.