An activist who scaled Buckingham Palace armed with a smoke grenade was cleared of possessing explosives on Wednesday (June 28).
After slipping past security, Martin Matthews, 50, and fellow New Fathers 4 Justice protester Bobby Smith, 35, used a ladder to climb the roof of the Queen's Gallery on November 29, 2015.
The duo unfurled banners, including one bearing the name of another group "Stop The War On Dads".
They also held press interviews during the eight-hour stand-off.
Police officers, clad in climbing gear and protective helmets, eventually managed to bring the siege to an end at around 11pm that night, by safely leading the activists down to ground level where they were detained.
Matthews was later searched and found to be in possession of a discharged smoke grenade, Southwark Crown Court heard.
Smith was not charged over the incident.
Experts classed the object as an explosive compound but Matthews insisted he had no idea and told police he only "wanted to cause a little bit of smoke for the purpose of a photograph".
After 45 minutes' deliberations, a jury found him not guilty of possessing explosives. But he may now face a trespass charge when his case is sent back to a magistrates' court.
Matthews and Smith were part of a group calling for equal rights for fathers in divorce and separation proceedings and for a reform of the family courts to prevent fathers from being stopped from seeing their own children.
The Queen's Gallery, which was closed off during the stunt, is a public art gallery containing a host of Royal Collection treasures including portraits of Her Majesty.
It sits to the left rear of Buckingham Palace but is not classed as an official Royal Residence and it is not believed that either The Queen or Duke of Edinburgh were home at the time of the security breach.
"Throughout the time Mr Matthews and Mr Smith were on top of the roof, of course it was their purpose, they received a lot of attention from members of the press," Mr Kent said.
"Many of them spoke to them while they were up there – they were actually conducting press interviews while on the roof.
"The purpose of those was to attract maximum publicity for their campaign. The particular focus of this case is not in fact the question of trespass.
"It is not a case directly concerned with whether the Crown say these men trespassed on to the site of Buckingham Palace. Rather, it is an item being carried, and indeed was used, by Mr Matthews.
"It is an explosive item – a smoke grenade – of the type that one normally might see being used in paintballing."
Matthews "accepted having used it on the gallery roof" during a subsequent police interview after officers found it in his rucksack but denied knowing it was an explosive during trial.
"In summary, he [claimed he] had wanted to cause a little bit of smoke for the purpose of a photograph," said Mr Kent.
An explosives expert found the "potassium chlorate-based low explosive" was capable of causing alarm or distress in addition to respiratory problems with the potential to ignite combustible materials.
"It was an unlawful protest in which Mr Matthews and Mr Smith climbed on to the roof of Buckingham Palace and refused to come down for six hours," the prosecutor added.
But Matthews, of Middlemead Road, Bookham, Surrey, denied knowingly being in possession of explosives and was cleared by the jury.
In October 2015, he had climbed on to the roof of MP Chris Grayling’s Ashtead home and a month earlier he scaled the Westgate fortified gateway in Winchester dressed as Batman.
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