The families of two 17-year-old boys who killed themselves after being arrested are delivering a petition to Downing Street, calling for a change in the law.

Nick and Jane Lawton's son Joe committed suicide two days after he was arrested for drink-driving last August.

Adrian and Ann Thornber's son Edward also took his own life after being summoned to court for possessing 50p worth of cannabis.

In both cases the parents were not informed of the arrests because their sons were treated as adults in custody.

The families have now joined forces to call for the Government to address the "anomaly" that 17-year-olds are treated as adults when arrested but as children if they are charged.

Mr Lawton told BBC Breakfast that he hoped the "groundswell" of public support would encourage ministers to act after more than 50,000 people signed the petition.

"Joe was our only child so we're not doing this for ourselves," he said. "We don't want other families to go through what we went through. It's dreadful."

Mr Lawton said Joe felt "ashamed" and "embarrassed" about his arrest but he was denied the chance to offer support to his son, adding: "But we were denied that opportunity to help him because at no time while Joe was in custody were we told of that. Very few people are aware of this anomaly in the law - whilst in custody they are treated as adults but as soon as they're charged they are then treated as children. How can you be an adult one moment and a child the next? That simply isn't right."

Both families say that if the law is changed it will bring the UK into line with the United Nations convention on the rights of the child. It states that every person under 18 must be treated as a child if they are considered such in the eyes of the law of that country.

A judicial review into the issue is ongoing.