Aristocrat Constance Marten’s newborn baby was exposed to conditions which created a “substantial risk” of hypothermia before her death inside a tent off-grid in winter, according to an expert.
Professor George Havenith examined the climatic conditions inside the tent and studied the microclimate inside layers of the Ms Marten’s clothing in weather conditions on the South Downs between 8 and 10 January 2023.
He told jurors at the Old Bailey that if the mother’s clothes and sleeping bag had remained dry, there was “just about enough” insulation to keep the baby safe.
However if the clothing and tent got wet, the baby would have been in danger of hypothermia.
He told the court: “Baby Marten, in the conditions stated, especially where moisture was present in the clothing both in the tent and on the way to the South Downs, would have been exposed to substantial climatic cold stress which would have led to a substantial risk of hypothermia.”
Ms Marten, 37, and Mark Gordon, 50, deny gross negligence manslaughter and causing or allowing the death of the infant, whose birth they concealed after their four other children were removed from their care.
The court previously heard how Ms Marten gave birth in secret at a holiday cottage in Northumberland and travelled the country by taxi, moving from location to location amid a high-profile manhunt for the missing parents, before settling off-grid in the South Downs in January 2023.
The prosecution alleges the parents at times used a red Lidl bag-for-life to carry the newborn, called Victoria, as they fled the authorities before her eventual death due to hypothermia or “grossly negligent co-sleeping”.
By the time they settled in the South Downs on 8 January 2023 in a “thin and flimsy” tent they were “sopping wet”, prosecutor Tom Little KC said when he opened the retrial last month.
When the baby’s body was eventually found stashed a rubbish-filled carrier bag by police in February, she was only wearing a baby grow.
On Tuesday, jurors heard evidence from the chartered ergonomist who conducted experiments on the risk of hypothermia to Victoria.
Professor Havenith told jurors that he took account of the temperatures in January 2023 as well as the impact of wind and moisture. As well as conditions inside and outside the tent, he also examined the microclimate between layers of clothing worn by Ms Martin, the court was told.
Prosecutor Joel Smith KC asked: “If the baby were wearing only a babygrow with those temperatures either outside or inside a tent without a sleeping bag, what would be the risk of hypothermia?”
Professor Havenith replied that the risk “would be very high”, adding that the sleeping bags purchased by Mr Gordon were not fit for the conditions.
Asked about the impact of not having a mattress, he told jurors that it was an “essential” item and a sleeping bag was not an effective insulator.
The professor said an adult in a dry tent would have avoided hypothermia but would find it “very uncomfortable”.
He added: “Wet clothing reduces your insulation quite substantially. It means you will have to shiver harder. The stress on the adults would become bigger.”
An experiment with two PhD students – in appropriate clothing – breathing in a tent resulted in condensation running down the walls and on the floor, the court was told.
Prof Havenith told jurors: “Based on experience I would expect condensation to occur.
“It would not directly affect temperature, but water on walls and floor will be absorbed by clothing. I would expect the clothing to absorb more moisture.”
Ms Marten and Mr Gordon both deny charges of gross negligence manslaughter of Victoria and causing or allowing the infant’s death.
Last year, they were convicted of concealing the birth of the child and perverting the course of justice in a previous trial.
The retrial continues.
