A special forces soldier was left a “dead man walking” after surviving being shot in the head while fighting the Taliban in Afghanistan, an inquest heard.

Corporal Alexander Tostevin escaped serious injury after being shot in the helmet while serving with the Royal Marines in Sangin in 2010.

The bullet skirted the inside of his helmet and he fell to the floor, but he got up and returned fire, allowing two of his comrades to get to safety.

The inquest in Bournemouth heard that the 28-year-old was mentioned in dispatches for his bravery.

He later joined the Special Boat Service (SBS) and he was serving with the Poole-based unit when he took his own life in March 2018.

The inquest has heard how Cpl Tostevin, from Guernsey, was left alone on the weekend he died with just a list of phone numbers for support.

At the time of his death, he was facing disciplinary action for going absent without leave and was receiving support from a Royal Navy welfare officer.

She told the inquest that Cpl Tostevin attributed his change in behaviour and attitude to life to his tour in Afghanistan.

“He mentioned that his whole outlook on life changed post-2010. He mentioned he felt like he was a dead man walking,” she said.

“He mentioned he had never smoked beforehand, and he had started smoking as a stress-release post those events.

“He spoke about night terrors and a mushy head and how he found it difficult to have intimate relationships with a girlfriend because he was worried he might punch out and hurt her in her sleep.”

The welfare officer said Cpl Tostevin would describe having “survivor’s guilt” because he felt there were those in a worse position than himself.

“He would often compare himself and minimise some of the feelings he had compared to people who had lost limbs or lost their lives in combat,” she said.

“He would often compare that because he still had his legs and his life that he felt guilty going forward and was still alive post-operational combat.”

Asked about changes in his behaviour, she said: “He mentioned taking excessive risks that he hadn’t taken before, having no regards for his own safety and spending money excessively and an increase in alcohol.”

The welfare officer had been assigned to work with Cpl Tostevin after he had gone absent without leave in London in September 2017 and used a military credit card to buy cocaine and hire a prostitute, after which he would kill himself.

The witness described Cpl Tostevin as being hypervigilant and having a high state of emotions.

“It was how he presented on multiple occasions. His pupils were dilated, he was jittery, nervous and agitated and distressed,” she said.

She went on to describe a conversation she had with him while they were returning from a meeting with the military charity Rock 2 Recovery.

“He was mentioning about taking tablets and Googling how many tablets to take to not be here anymore and that he was really low,” she said.

Following that conversation, she emailed Cpl Tostevin’s superiors, as well as his GP and community psychiatric nurse, sharing the details.

The inquest also heard from Cpl Tostevin’s GP, who when told of the London incident thought he might be having a hypo-manic episode.

He saw him at the end of September and believed he was exhibiting some symptoms common with PTSD. He downgraded his rating within the SBS, which meant he was put on restricted duties.

He saw him again in February 2018, when he rated Cpl Tostevin as fit for frontline duties due to improvements in his mental health.

Kirsten Heaven, representing the Tostevin family, asked the welfare officer whether she thought her opinion on Cpl Tostevin returning to regular duties was given any “weight, respect or credence”.

The witness replied: “I didn’t feel it was given any respect or credence. However, because he was under the medical model, the medical model in this situation took precedence,” she said.

Ms Heaven asked: “Did you know on the day the decision was taken for Alex to be returned to the unit he was at the same time telling the community psychiatric nurse that he had fleeting suicidal thoughts?”

The witness replied: “I did not know that.”

The inquest continues.