Tania Clarence planned to kill her three disabled children before suffocating them with a nappy while they slept at their New Malden home, the Old Bailey has heard.

Clarence today (14 November) left the dock in tears during her sentencing and was allowed to return to hospital as the prosecution detailed how she killed four-year-old Olivia, and three-year-old twins Ben and Max in April before placing toys beside their corpses.

The court heard how she smothered her children on the birthday of her eldest child's birthday and that letters she had written suggested she had plotted their deaths.

It also emerged the South African native left the family nanny a note saying: "I am so sorry I had to do this but I can't carry on."

The 42-year-old pleaded guilty at an earlier hearing to the manslaughter of her children by diminished responsibility.

Olivia, Ben and Max suffered from spinal muscular atrophy, a genetic disorder which leaves children with little control of their movements and can drastically shorten life expectancy.

Clarence's husband Gary was reportedly away in South Africa with the couple's eight-year-old daughter when the deaths happened.

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