In reply to elsewhere:
The BBC article suggest the biggest hangup is a commercial one - the primary age verification company also being an owner of porn sites.
The whole point is to stop children accessing inappropriate content - not sure this will ever be achievable - as a work around will soon be found by a determined kid. Stolen IDs will be passed around whatsapp the moment the ID wall comes down.
I see that it will only apply to sites which have at least a third of their content being adult content.
I wonder how quickly there will be websites hosting 33% adult content and 67% of something completely unrelated.