THE Court of Appeal has reserved judgement on an appeal by a former Bromsgrove couple jailed for the "salt overdose" killing of a three-year-old boy.

Lawyers for Ian and Angela Gay, now of Halesowen, have asked the court to accept evidence that Christian Blewitt could have died of natural causes as a result of a type of "salt diabetes".

But the prosecution argued on the third day of the hearing last Thursday that the hypothetical evidence should be rejected because it was not new and simply revisited past issues.

Ian Gay, aged 39, and his 40-year-old wife were each jailed in January last year for five years for manslaughter following a seven-week trial at Worcester Crown Court.

The child they planned to adopt died in hospital four days after being found unconscious in his room on December 8, 2002, at the £500,000 Bromsgrove house where the wealthy childless couple then lived.

The former engineer and his wife, a £200,000-a-year insurance actuary, always insisted they loved Christian, and his siblings who were also in their care.

Defence lawyers argued that, had the fresh evidence been available at trial, the jury's verdict could well have been different.

As it was, the jurors were presented with just two options - either the couple murdered Christian by blunt force to the head or were guilty of manslaughter by feeding him salt as a punishment.

According to a new witness, Dr Glyn Walters, the boy was not a victim of salt poisoning and could have been suffering from a rare condition, which allowed sodium levels to build up in the body to overload.

The condition could explain why Christian had so much sodium in his system.

Last Thursday crown counsel William Davis QC reminded Lord Justice Richards, Mr Justice Penry-Davey and Judge Ann Goddard that there were other factors in the case apart from medical evidence.

It was suggested that bruising to the child's head was caused while he was being held down and forced to take salt.

This was among factors the court should bear in mind in deciding, he said.

The judges did not set a date for delivery of their judgement.