Except that in the UK we do have freedom of speech - just go to Speaker's Corner in London and hear all the nonsense spouted by idiots with all kinds of conspiracy theories.
None of them are doing it anonymously.
Many others in the UK have spoken out with dissent for the government's intentions. Sometimes it works and they change, most of the time they just ignore us and do what they were going to anyway.
I think the difference is that, even though you're not truly anonymous online either, too many fuckwits think they are and it affects their behaviour. Look at the recent twitter arrests and imprisonments for doucebags who thought it was ok to spout death threats online.
So all they're really saying is that you should be more open about who you are online, as the authorities can find you anyway if they dislike what you've said. Removing the appearance of anonymity may make those morons change their behaviour online, and will make finding you cheaper when (or if) you say things worthy of police action (I assume if you're worthy of special branch attention, they will already know who you are with a quick call to GCHQ)