A Colchester family is appealing for funds to take their selective mute son – who will not even cough, sneeze or hiccup outside of his home – to America for treatment.

Bobby Daley, eight, is described as a chatterbox at home, but has never spoken a single word at school due to his condition.

He only ever speaks to five people – his mum and four siblings – with even his dad, step-dad, grandparents and aunts and uncles frozen out.

His football team mates have never heard him call for the ball or celebrate a goal.

Desperate for help, his family are now turning to experts in America to unravel the crippling anxiety that causes him to stay silent, despite being a perfectly capable speaker.

Mum Georgina said: “When he’s with me he never stops nattering and if you heard him playing with his brothers you’d never know that anything was wrong. We can’t shut him up in the house.

“Yet from the moment he leaves for school in the morning, that’s it – he’s completely silent all day until he walks back into the house.

“He won’t even cough, sneeze or hiccup. Even if he falls over and hurts himself in the playground, he won’t cry out in pain.”

Bobby, who likes Minecraft, Lego and fidget spinners, cannot even tell teachers he needs the toilet.

Selective mutism is classed as an extreme anxiety disorder that affects seven in 1,000 children and adults.

The cause of the condition is unclear. Some sufferers are believed to have an inherited predisposition to anxiety, while in other cases some sort of psychological trauma can be a factor.

Georgina, 32, added: “Bobby does alright at school, which surprises people. He’s exceptionally good at maths and performs well in science and other subjects. He struggles a bit at English but that’s hardly surprising.

“He uses a whiteboard in the classroom to write things down, express himself and join in. The teachers do their best, and there’s one learning assistant who Bobby’s really close to and he shows her he trusts her by sometimes whistling, yet he’s never spoken to her.

“People often assume Bobby’s just rude. There’s usually a presumption he’s bad-mannered, but nothing could be further from the truth.”

Bobby has lots of school friends and communicates with smiles, frowns, nods and points – just not words.

Georgina, a florist, has been seeking help for Bobby since he was a toddler and she first realised something was amiss.

But so far GPs, mental health professionals and paediatric consultants have been unable to make a break-through, and he still only speaks to Georgina and his sister Lola, 13, brothers Arthur, six, and ten-year-old Jude, and step-brother Jay, also 10.

Earlier this year Georgina attended an anxiety disorder conference where she heard about pioneering treatment in the US – intensive group behavioural therapy run by the Child Mind Institute in New York.

The five-day ‘Brave Buddies’ programme sees specially-trained psychologists coax youngsters into practicing ‘verbal participation’ through craft activities, sports and field trips.

Told that Bobby is fast approaching an age when the treatment starts to become less effective, Bobby is booked in to travel this month – and Georgina is now desperately trying to raise £6,000 to help cover the cost of the programme, plus travel for her and Bobby.

“The clinic has a high success rate, although nobody can guarantee success. But it’s something we simply have to do if he is to have any chance of leading a normal life as he gets older. I dare not think about what the future holds without a breakthrough,” said Georgina.

“His friends are incredibly accepting, but as he gets older that’s likely to change. How will he ever hold down a job if he won’t speak? And it’s hard to see how he could form a relationship or start a family.

“I’ll always be there for Bobby and I know how lucky I am he feels able to talk to me. But I long for the day when the rest of the world can hear his voice and words don’t leave him paralysed with fear.”

• To support Bobby’s fundraising donate here.