The judge said that the Stimson sentenced to eight years in prison, but subtracts a third of that time for an admission of guilt.
"We are shocked by the verdict. It's too harsh," he said in an interview to correspondent Bi-bi-si the Olga Ivshina the father of a convicted Martin Stimson.
"I'm sorry my son went there. We didn't know about it. We thought he was working on the farm", he added.
The prosecution said that Stimson had "the intent, with the assistance of other persons to commit acts of terrorism by joining the ranks of the militia opposing the Ukrainian authorities, and service as a militia fighter".
However, the judge found no evidence that Stimson was directly involved in armed conflict.
The judge ruled that Benjamin Stimson does not have extremist views and does not represent now danger to the population of Britain.
Initially, Stimson was also accused of preparing and committing terrorist acts, but then the charges were dropped.
A fighter against imperialism
Benjamin Stimson 41. He was born and raised in the North of England. In the fall of 2015, the journalists of Bi-bi-si, met him near Debaltsevo.
He said that he went to the Donbass, because the house did not see any prospects. At that time he was already a year and a half were without work.
But no less important for the British was and ideological reasons.
"I think what is happening is Western imperialist aggression against Russia, against people who don't play Western games," he said then Bi-bi-si. During the interview, Stimson held standing beside the chair carabiner.
However, he said that three months spent in the East of Ukraine, he has never shot at the enemy.
At trial, Benjamin Stimson denied involvement in the hostilities. According to him, he spent in the East of Ukraine four months, working as an ambulance driver.
According to the materials of the case, during his stay in the Donbass, the British spent several weeks in the hospital due to stomach problems, and then quite a lot of time was in the rear location of the forces DND, only occasionally coming to the front.
The armed conflict in Eastern Ukraine began in spring 2014. In its most active phase came in the summer of the same year. Kiev and Western countries accuse Russia of providing military aid to supporters of the breakaway Donetsk and Lugansk "people's republics".
Ukrainian authorities have repeatedly stated that in the East there are regular units of the Russian army. The Kremlin denies involvement of Russian military in this conflict, while emphasizing that there can be citizens of Russia, voluntarily taking part in hostilities.
In Britain legislation, according to which persons returning from countries where they have participated in armed conflict may be charged with terrorism.
This law came after hundreds of British citizens went to Syria to fight on the side of the extremist group "Islamic state".
Support Benjamin L. Stimson came to the court of his parents and friends.
Reports from Manchester correspondent of Russian service bi-Bi-si Olga Ivshina, his father was visibly nervous. His hands were shaking so much that he could not close the plastic lid of the coffee Cup.
He looked a little lost and often looked around. I think he still could not understand how his son has managed to get into this story.
Benjamin Stimson arrived in Moscow in early August 2015. Out with people with whom he met in social networks, the British crossed into the Donbass and joined one of groups of self-proclaimed DNR.
Stimson was detained at Manchester airport at the end of November 2015 - as soon as he returned to the UK. According to the materials of the case, he was questioned