Its actually an incomplete quote, in the summary text of the CPS guide.
The correct version is :
“Every citizen (whether Policeman or not)
in whose presence a breach of the peace is being, or reasonably appears to be about to be committed, has the right to take reasonable steps
to make the person who is breaking or threatening to break the peace refrain from doing so; and those steps in appropriate cases will include detaining him against his will short of arresting him
His conduct was nowhere close.