A four-year-old boy died after a succession of beatings by one of his foster parents, a jury was told today.

John Anthony Smith was in the process of being adopted by the Southwick couple and spent six months with them before his death.

During that time he suffered numerous injuries, bruises to his body, burns to his face and a cut to his penis, a jury heard.

Social workers accepted the couple's explanation that the boy was harming himself, even though they never took him to a doctor, Lewes Crown Court was told.

The boy died in hospital from head injuries on Christmas Eve 1999.

Simon McWilliams, 41, and his wife Michelle, 35, of Gardner Road, Fishersgate, Southwick, deny cruelty.

John died of a brain haemorrhage. His body had 54 separate external injuries including bruises to the face, neck, head, arm, legs and back plus four adult bite marks on the legs and arms, the court heard.

Opening the prosecution today, Camden Pratt QC said one of the defendants had inflicted the fatal injuries and each had failed in their duty to care for the boy.

He told the jury: "The Crown cannot prove to you which of the defendants delivered the blows that killed that child. That is why we are not trying a case of murder or manslaughter.

"It is why we are trying a case of cruelty, because although we cannot say which of the two, both must have known what was going on over a long period of time when this little boy was subjected to cruelty.

"One was doing it and the other knew what was going on and did not intervene, as is their duty."

Mr Pratt said the couple colluded and pretended the boy was harming himself. He said some injuries could have been accidental but not all.

Mr Pratt said neither the boy's natural parents nor his previous foster parents, Rod and Pauline Mears, reported any serious problems of self-harming.

A health visitor said the boy improved when he was in the care of the Mears and had stopped wetting the bed. He was described as an active boy who could sit quietly with a colouring book. He was emotional and "liked to be cuddled", the court heard.

The Mears reported during one meeting with the McWilliams couple after they had taken John Smith into their care that Simon McWilliams had "violently lost his temper" when discussing how to deal with the child, the jury heard.

Mr Pratt said two social workers, David Panely and John Barrow, made regular visits to the McWilliams' home.

He said the question would arise as to what extent these social workers spotted what was going on or "had the wool pulled over their eyes".

He said the McWilliams pair said the boy would throw himself downstairs, or into radiators, and rub himself on carpet.

The case continues.