Read those sections

So I've already dealt with the infamous section 44 of the Terrorism Act, not once, but twice.

I've looked at the new and scary section 76 of the same Act.

Now in the wake of the G20 protests it seems everyone needs to have a look at section 14 of the Public Order Act 1986 which as you can see form part of Part II "Processions and Assemblies" and comes with a 14, 14A and 14B. We can skip the A and B as they apply only to such events that occur on (essentially) private ground for which no permission has been granted.

So that leaves only the vanilla 14 that was quoted to remove journalists from an assembly so let's take a closer look.

14. — (1) If the senior police officer, having regard to the time or place at which and the circumstances in which any public assembly is being held or is intended to be held, reasonably believes that—
(a) it may result in serious public disorder, serious damage to property or serious disruption to the life of the community, or
(b) the purpose of the persons organising it is the intimidation of others with a view to compelling them not to do an act they have a right to do, or to do an act they have a right not to do,

he may give directions imposing on the persons organising or taking part in the assembly such conditions as to the place at which the assembly may be (or continue to be) held, its maximum duration, or the maximum number of persons who may constitute it, as appear to him necessary to prevent such disorder, damage, disruption or intimidation.

Okay read that then just the last paragraph again about what they can do. Can they "[order] 20 members of the media to leave the area for 30 minutes under the threat of arrest" under this section - nope. They could have set a maximum duration for the assembly of say 5 minutes; they could have set a maximum number of people who can be there.

Then under section 14(5) they could have been arrested for failing to comply with the above directions except here's the exact quote

A person who takes part in a public assembly and knowingly fails to comply with a condition imposed under this section is guilty of an offence, but it is a defence for him to prove that the failure arose from circumstances beyond his control.

"A person who takes part". Can the media be said to be "taking part"; unlikely. Yep either the officer was showing their ignorance of the law, or counting on the media's.

So the police are asking for the deletion of photographs under section 76 (which they can't do) searching without cause under section 44 (which they can only do in specific areas as authorised) or basically clearing the media out under section 14 (which they can only do along with everyone else there and only by defining the media as "taking part" in the assembly).

Lovely! That'll stop instances of police abuse ever being made public won't it.