A former South Craven soldier and a Yorkshire Regiment colleague who were gunned down by a rogue Afghan policeman inside their checkpoint were unlawfully killed, a coroner has ruled today.

An inquest heard that Sergeant Gareth Thursby, a former pupil at South Craven School, Cross Hills, and Private Thomas Wroe, from Holmfirth, died of multiple gunshot wounds after the man, a member of the Afghan Local Police, opened fire on them at a checkpoint in Helmand Province on September 15 last year.

Oxfordshire Assistant Coroner Alison Thompson said there was no apparent motive for the man opening fire on British troops, killing Sgt Thursby, 29, and Pte Wroe, 18, and there was no established link between him and the insurgency in Afghanistan.

Oxford Coroner's Court heard that a third soldier was injured after being shot several times in the incident, which came in a spate of "green-on-blue" attacks - where members of the Afghan security forces turned on their coalition colleagues - in the latter part of 2012.

Recording a verdict of unlawful killing for both men, who were from the 3rd Battalion, The Yorkshire Regiment (Duke of Wellington's), Ms Thompson said: "It is often difficult if not impossible to establish motivation in this sort of case, making it especially hard for families to come to terms with the death.

"And I am sorry that I am not going to be in a position today to provide a reason for this appalling attack as I have heard no evidence as to why it took place and therefore it would be wrong and improper for me to speculate in any way."

The inquest heard that the Afghan local policeman was visiting the checkpoint, called Tora, in Nahr-e Saraj, from another one nearby when he opened fire.

He was well-known to the men there and was known to be "pro-Isaf (International Security Assistance Force)" and a "champion of the partnership" with the coalition.

The man, known as Gul Agha, had been laughing and joking with soldiers at the checkpoint before he turned his AK-47 on them.

The inquest heard that Afghan security forces were required to make their weapons "safe" when entering the checkpoint, but did not have to unload or hand them in, and it was not known whether the man had made his safe.

Lieutenant Callum Cameron, platoon commander of 3 Platoon, Alma Company, told the inquest all Afghan Local Police (ALP) visitors were checked and vouched for by colleagues before they were allowed into the checkpoint, and the man in question had been vouched for.

Soldiers from 3 Yorks who gave evidence to the inquest described the shock that the man, who was known to them, had turned on them.

As he sat at a table with the soldiers, he opened fire, injuring one private, killing Pte Wroe who was hit four times, missing two other soldiers, and then killing Sgt Thursby, who was shot five times. Fellow troops shot him dead.

Giving her verdict, the coroner said it was "impossible to entirely legislate" against the threat of insider attacks, because of the importance of building relations.

She told the families: "I can only hope that by hearing from Gareth and Thomas's colleagues today at least you know exactly what happened."

Speaking outside the inquest, Pte Wroe's father, Michael, said he did not want to point the finger at anyone, and they now knew what had happened to their son and to Sgt Thursby.

"We would like to thank the soldiers for talking today and explaining to us what happened," he said.

"Just thanks for their help and we hope that lessons can be learned from this."

The inquest was also attended by the parents of Kingsman Ryan Ward, who shot the Afghan gunman dead, but later killed himself.

An inquest into the 20-year-old's death previously heard that he was found hanging at his family home the day after Sgt Thursby's funeral.