Meanwhile, more than a quarter believed that autistic children are just naughty and only 14 per cent are aware that 1 in 100 children have autism.

Jolanta Lasota, chief executive of Treehouse, said: "The low level of public understanding is causing families to feel self-conscious, isolated and judged. We know that some families even avoid going to public places.

"By talking about autism we can make a start on giving children and families the support they deserve."

Treehouse has launched a new campaign called Talk About Autism, in an attempt to improve public understanding of the condition.