An autistic British man who tried to grab a police officer’s gun at a Donald Trump rally will “never set foot outside the UK again”, his mother has said.

Michael Sandford has “realised what the special things in life are” and wants to stay at home in the UK after his traumatic spell in prison, Lynne Sandford told The Independent in an exclusive interview from Las Vegas.

The 20-year-old was sentenced to 366 days in jail this week over his plan to shoot the 70-year-old President-elect. But he could be home in four months because of custody time already served.

As well as suffering with Asperger Syndrome, the Robot Wars fan from Dorking, Surrey has struggled with anxiety, severe obsessive compulsive disorder, anorexia, hypersensitivity, seizures, severe depression and Crohn’s disease, Ms Sandford said.

Lynne Sandford and son Michael when he was growing up (PA)

“He doesn’t want to travel anymore,” she added. “He said ‘I wish I listened to you mum’ when he was deciding to go out to America. He said he’s never setting foot outside of the UK again. He’s realised what the special things are in life, especially his family.”

Her son, who at age 12 passed a mock GCSE exam with an A, dropped out of education after a series of truanting episodes and bullying during his early secondary school years. At 16, Michael found himself a one-bed flat a few minutes from the family home, paid for with disability, employment and housing benefits.

Ms Sandford said she had spent many years begging British mental health services for help and blamed them as "the cause of all of this”.

“I went back and forth to them for years, saying my son has issues and problems, and I was told I was a paranoid parent,” said the 42-year-old mother-of-two.

Her son gradually stopped Lynne, grandmother Christine and baby sister Jessica from visiting however, and on New Year’s Eve 2014, stunned them by saying he was going to New York.

Lynne Sandford and lawyer Saimo Chahal at a press conference in London in August (Justin Tallis/AFP/Getty)

Ms Sandford still worries federal prosecutors will launch an appeal against the sentence (Justin Tallis/AFP/Getty)

Ms Sandford, who dotes on Michael, desperately tried to stop him, appealing to her GP and the mental health service for help. But his learning disability and health record did not necessarily brand him as dependent in the eyes of the law.

“We were horrified,” said Lynne. “That someone always so reclusive wanted to do something so out of character. They said 'he is 18, he is an adult', even though he’s vulnerable.”

The first fleeting trip was a disaster, having suffered a mental breakdown and been sectioned on his first night in the States, but with a chunk of inheritance money, he returned again.

Sandford's mother speaks

In May this year, after he stopped contact, Lynne reported him missing, and in June, she saw him being frog-marched out of the Trump rally on the news.

When asked why he reached out to grab the police officer’s gun, he reportedly told officers that he planned to shoot Mr Trump.

The 18 June incident was retrospectively diagnosed as a psychotic episode, and Ms Sandford said: “Not at all did he really try to shoot Donald Trump. He would know in his subconscious that he didn’t stand a chance. He knew that he would be wrestled to the ground. The judge described it as a ‘crazy stunt’ and thankfully he was very accepting.”

He pleaded guilty to being an illegal immigrant in possession of a weapon and of disrupting government business, and faced potentially up to 10 years in jail.

An emotional birthday letter from Michael Sandford for four-year-old sister Jessica and the family (Lynne Sandford)

He was sentenced to 12 months and one day. Because of time already served, he could be released home from South Nevada correctional centre in four months' time thanks to good behaviour.

“I’m extremely elated and very relieved,” said Ms Sandford, adding that they had worried that Mr Trump's election might have a bearing on the sentence.

“It’s phenomenal news,” she said.

Autism: Can you make it to the end?

She said that both she and a very remorseful Michael, know that he deserved a firm sentence for what was a serious security scare, but they feared the US judicial system might have been unforgiving.

Nevada has three mental health courts, but the criteria for offenders to qualify for them is high and Michael was prosecuted by federal, not state law.

There is also still a looming threat of a possible appeal against the sentence by prosecutors.

“Prison has been torture,” said Ms Sandford. “He has not known how to get through it. I try to boost his morale but it’s been so brutal and quite horrific.

“When he is on suicide watch, he is locked up 24 hours a day, seven days a week, and at times, stripped of clothes and not allowed toilet paper because it can be rammed down the throat."

Michael, who has received death threats in jail, has also struggled to sleep at night because the cell lights are so bright.

For an autistic person with depression and anxiety, who takes everything very literally, and who has unpredictable bowels, it has been a nightmare, Ms Sandford said.

“It remains to be seen where he’ll live when he gets back and he’ll probably have post-traumatic stress disorder,” said his mother, who arrives back home on Friday after a whirlwind week of near-sleepless nights and media attention.