"... is a criminal offence in England."

No, it's not, it's not a criminal offence anywhere in the Western world for security guards to do such a thing.

I read the article - I didn't miss those quotes.

I think you are missing something important:

* charges laid *

Meaning that there are legal charges against those two - indicating they had possibly done something illegal.

While I agree it's 'confusing' that one of the library staff, for whom the security guard may have ostensibly been working - implored the guard to 'not kick the man out' - I don't this resolves the question.

"as part of the agreement nobody was to be prevented from asking a controversial question and the security team would consult with library officials before ejecting any nonviolent patrons"

I get that - but was the guard acting on his own here?

It remains unclear to me - which is my point.

If this security guard was acting entirely on his own initiative, and just kicking a guy out for asking 'controversial' (and let's be fair: insulting and stupid) questions, then yes - there's obviously something crazy going on. Why were they ejected?

But I'm not sure it's clear from the article, which is my point.

"Ask me to leave [and] I will leave.” - obviously someone was asking him to leave.

I think the writer did a poor job of articulating the situation.