A detective inspector has told a trial at the Children's Court that he did not mention the accused teenager in his original statement as there were hundreds of people around.

During cross-examination Detective Inspector Derek Maguire also agreed that some of those present at a demonstration in Tallaght in 2014 were urging other protesters not to throw things.

A 17-year-old boy is on trial charged with falsely imprisoning then tánaiste Joan Burton and her adviser in two garda cars during a protest in November 2014. He denies the charge.

On the third day of the trial the court has been shown video footage of the protest.

Detective Inspector Maguire told the judge the defendant can be seen in the footage holding a megaphone and standing in front of a garda Jeep with Ms Burton inside.

The Garda Public Order Unit was trying to clear the crowd.

The Inspector also said the defendant appears to be clapping in another part of the footage and is gesturing to the crowd with arm movements.

The court also heard the defendant may have said into the megaphone at one stage "Joany in your ivory tower - this is called people power".

This afternoon, Detective Inspector Maguire denied reaching an agreement with demonstrators at the protest in Tallaght two years ago to allow a slow march to take place in front of the car carrying Ms Burton.

Defence Counsel Giollaíosa Ó Lideadha said the video footage taken on the day of the protest clearly shows a slow march taking place immediately after the Garda Public Order Unit had withdrawn.

Mr Ó Lideadha said this was consistent with an agreement being reached and pointed to the Inspector’s statement, which said protesters had said they wanted to slow march Ms Burton’s car out of Tallaght.

Inspector Maguire said he had made several requests for the protesters to move on and allow the garda vehicle to leave but at no stage did he make any agreement with the demonstrators.

He said he made the requests under the Public Order Act and they were not complied with.

Mr Ó Lideadha said the garda's evidence that the protesters would not communicate with him was simply not credible because there was evidence of a request for a slow march if the public order unit was withdrawn and that is exactly what happened.

Inspector Maguire again insisted there had been no agreement.

Mr Ó Lideadha also pointed to footage that showed the teenager walking and encouraging others to do so.

Inspector Maguire agreed but said this was two-and-a-half hours after the protest began.

He also pointed to footage that showed the accused standing behind those sitting on the ground but not sitting himself.

Det Inspector Maguire agreed that the defendant had not sat down "in that particular piece of footage". He also agreed with counsel that the defendant could be seen holding a megaphone for a woman who was urging people to stop throwing eggs.

Mr Ó Lideadha said his client could also be seen on the footage "strolling around the place not causing any trouble to anyone".

He also put it to the Inspector that the defendant could be seen gesturing to others to move forward. He agreed that he could.

During re-examination by prosecuting counsel Tony McGilicuddy, the Inspector said the defendant was earlier among a crowd of protesters who stood behind a garda car carrying the then tánaiste and prevented it from leaving St Thomas' Church.

Mr Ó Lideadha said this was a new claim being made by the prosecution, which had not been made in direct evidence and it was "totally wrong and totally unfair". He said there was nothing to support this claim.

He also said the defendant by his hand gestures and the use of a megaphone was orchestrating the crowd. Mr Ó Lideadha said such orchestration was asking the crowd to move on.

Defendant identified from video footage

Meanwhile, Sergeant Michael Phelan told the court he identified the defendant from a screen-shot taken from video footage.

He said he recognised him as one of those who had blocked Ms Burton as gardaí tried to escort her along a footpath between An Cosán and St Thomas' Church.

He said the crowd had surged towards her and gardaí had to form a cordon around her.

The protesters blocked their path and some clung to railings forcing the group to stop walking a number of times.

The defendant was among this crowd, Sgt Phelan said, and he had to physically push him forward with his shoulder in order to escort Ms Burton into the church, he added.

He also said the defendant had urged demonstrators to enter the church grounds when it became known that gardaí were going to try get her out in an unmarked car.

He said the accused teen was among those who surrounded the car and was using a megaphone to encourage people to chant.

The protesters were ordered to move under the Public Order Act but it was to no avail, according to Sgt Phelan.

"There was constant jostling and pushing and gardaí were being shoved and pushed and had their caps knocked off.

"One female colleague was pushed from behind and fell into the crowd. The protesters just could not be moved," he told the court.

Sgt Phelan said protesters sat in front of the garda vehicle and as one protester was moved another one or two would move in.

Missiles 'rained' down on gardaí, court told

He said missiles rained down on gardaí including coins, cigarette lighters, branches of trees and other items. He said he was hit with a can of Red Bull and the window of the garda vehicle was damaged.

When the slow march began there was a change and no resistance came from those in front of the vehicle but the crowd on the periphery were still shouting and another sit down protest began, the court heard.

He said there was a suggestion from one of the perceived organisers that if the public order unit moved out, the slow march would resume.

During cross-examination Sgt Phelan was shown footage that showed the defendant moving along the footpath while filming.

Defence counsel said his client appeared for the most part to be moving backwards while filming.

Mr Ó Lideadha said the pushing and shoving only happened because other people had come behind his client and he could not continue moving back.

Sgt Phelan said he had to use force to remove the boy from blocking his way.

Sgt Phelan agreed with Mr Mr Ó Lideadha that there were occasional periods of calm during the protest. 

Teenager 'sorry' for wasting Garda time

The court heard details of the teenager’s arrest in February 2015 when he was detained at Tallaght Garda Station to be questioned. 

Garda Damian Reilly said the boy was questioned in the presence of his mother and he declined to have a solicitor present.

The boy, who was 15 at the time, was told he was being questioned in connection with a false imprisonment charge and he said he understood.

CCTV footage and photos were shown to him and he identified himself, including footage of him in a "slow march", but said he did not engage in a sit down protest.

It was put to him that he could be seen instructing the crowd but he denied being a leader or organiser of the demonstration. He said he found out about it online.

Garda Reilly asked him if he was sorry and he replied "yes".

He was asked was that for participating and he said "basically yes".

He was then asked if he was sorry for participating or for causing criminality and the teenager answered: "for participating, and the stress I am learning I placed the tánaiste under".

He also said he was sorry for wasting his mother's and garda time.

Garda Reilly agreed with the defence that the teenager addressed the upset he caused to Ms Burton and Ms O'Connell.

The court heard he had no prior criminal convictions or other charges pending and was getting good marks in school. The teenager also told gardaí that he did not have any family problems and did not hang around with many people.

The case was adjourned until Friday to set dates for the resumption of the trial.