Ian and Angela Gay always denied poisoning Christian Angela Gay reaction

Christian Blewitt collapsed at the couple's home in Bromsgrove, Worcestershire, in December 2002.

Ian and Angela Gay, now of Halesowen, West Midlands, were found not guilty of manslaughter and child cruelty.

The pair had previously been convicted of his manslaughter, but won a retrial because of new medical evidence which said the high salt levels were natural.

Prosecutors at Nottingham Crown Court had claimed the couple had force-fed salt to the boy as a form of punishment.

We have waited for years for this moment and finally justice has been done Angela Gay

But the pair's defence team argued a rare medical condition caused Christian's body to store toxic levels of salt.

Two years ago the couple were jailed for five years after being convicted of manslaughter.

They served 15 months of that sentence before a retrial was ordered in April last year and the couple were released on bail.

Found comatose

Christian was just five weeks into a 13-week trial adoption with the couple when he collapsed.

After four days in intensive care, he died at Birmingham Children's Hospital and tests showed the high sodium levels.

The couple's retrial was told that in the hours leading up to the boy's collapse, Christian had been sent to bed as a punishment for not eating his lunch. He was later found comatose in the bedroom.

Why were salt levels high?

Prosecutors had said he had collapsed because the couple had force-fed him salt because of his misbehaviour.

They had also manhandled the boy, the prosecution argued, shaking him or throwing him on to a mattress so as to cause the bruising to his head.

After the verdict, Mrs Gay, 40, read out a short statement on the steps of the court.

"We have waited for years for this moment and finally justice has been done," she said.

"We would like to thank our family, friends, and legal team. They have been wonderful.

Retrial 'was right'

"They have all supported us so magnificently and we would now appreciate some time alone to gather our thoughts before commenting further."

Leading barrister Michael Mansfield, QC said cases based on conflicting arguments from experts, such as this, should not be brought to court.

"You're presenting a jury or a judge with an impossible task.

We believe we were right to place it before a jury for the second time Crown Prosecution Service

"How do you choose between accredited experts and I don't think that that's possible and I don't think that those cases should be prosecuted in the first place."

The Crown Prosecution Service (CPS) has defended its decision to pursue a retrial in the case.

In a statement, it said: "In the light of the new medical evidence, we believe we were right to place it before a jury for the second time.