Constance Marten caused her newborn baby's "entirely avoidable" death, a court heard as she and her partner went on trial for a second time accused of killing their daughter by going on the run with her.
The 37-year-old mother, who comes from an aristocratic family, gave birth in secret after her first four children were taken into care and then, along with Mark Gordon, 50, went "off grid", camping out with their daughter in freezing conditions on the South Downs, a court has heard.
The newborn baby died in January 2023 and Ms Marten and Mr Gordon are accused of manslaughter by gross negligence and causing or allowing the death of a child.
The couple stood trial in 2024 but jurors were unable to reach verdicts on the two charges.
Jurors at the Old Bailey retrial were told that the pair had previously been found guilty of perverting the course of justice and concealing the birth of a child.
Opening the case for the prosecution for a second time, Tom Little KC said the case involved the "entirely avoidable death of a young baby".
He said the baby would still be alive today if it were not for the "reckless and ultimately grossly negligent conduct" of the defendants.
Mr Little went on: "They put their relationship and their views of life before the life of a little baby girl.
"Rather than act in the obvious best interests of a vulnerable baby and one that they should have cared for and looked after, they decided instead that they knew best.
"They decided that in the middle of winter and in obviously dangerous weather conditions they would deprive the baby of what it needed - warmth, shelter, protection and food and ultimately safety.
"They essentially went off grid and lived in a tent with hardly any clothes, no means of keeping and remaining warm and dry and with scarcely any food.
"They did so when they were both exhausted from having been on the run for a number of days. Their desire to keep their baby girl led inexorably to the death of that very baby."
Jurors were told that Ms Marten and Mr Gordon had been in a relationship since 2016 and had four older children. But he said following "extensive social services interaction", all of those children had been taken into care.
Mr Little explained that when Ms Marten became pregnant in 2022 with her fifth child, she and Mr Gordon sought to keep it secret.
"No doubt because they knew that the child would be taken into care, this pregnancy and the subsequent birth was concealed from everyone including family and friends, healthcare professionals and social services," the prosecutor said.
Ms Marten, who was in the glass dock at Court 5 of the Old Bailey, sat listening intently to proceedings. Mr Gordon was not present but jurors were told it was hoped he might be able to join later.
Explaining the couple's alleged movements during late 2022 and early 2023, Mr Little said on Dec 20 they had booked into a holiday cottage in a remote part of Northumberland.
After several days, they "left in something of a hurry", leaving rubbish strewn around the cottage. However, the bedding had been freshly washed.
Mr Little said over the following days, the defendants travelled across the country, rarely staying in one place for more than a couple of days.
However, on the evening of Jan 5 2023, their car caught fire on the M61 motorway in Greater Manchester. The couple fled the scene but police subsequently found several "burner mobile phones", Ms Marten's passport and a placenta wrapped in a towel.
"The finding of the placenta revealed the existence of a newborn baby girl," Mr Little said.
As a result of the discovery, a high-profile missing person's appeal was launched as the couple went on the run, paying hundreds of pounds for lengthy taxi journeys.
Mr Little said that money was not a problem because Ms Marten came from a "very wealthy family".
He added: "She has a trust fund. She had potential access to money and you may have thought whatever help she needed had she chosen to do the right thing rather than make bad decision after bad decision."
At one point, the couple had been in east London where they bought a buggy.
But Mr Little said a short time later they had taken the "extraordinary decision" to abandon the buggy, transferring the baby into a "red reinforced Lidl bag for life, where it would appear she spent some of her life before she died".
He said: "It would have been plain to the defendants, you must have thought, that this was an utterly inappropriate way to care for any child, let alone their child, and remember at all times in this case the time of year and the weather conditions and the lack of clothing that there was for the baby."
The court heard that by January 2023, after criss-crossing the country with their baby, they were camping in a tent on the South Downs.
Mr Little said: "The weather was relatively cold, wet, windy and dark. It was not warm. This was not the summer. This was the last place that the defendants should have been, you may think, with such a young baby. The risks and dangers were obvious."
Ms Marten later told the police the baby died on the first night in the tent after she accidentally smothered her while co-sleeping.
The couple remained at large for several more weeks, becoming so hungry at one point that they began scavenging in bins for food.
They were eventually arrested on Feb 27 2023, after they withdrew money from a cash machine to buy food.
They were dishevelled and smelt as if they had not washed in weeks. The baby was not with them and they refused to tell police where she was or whether she was still alive.
On March 1, 2023, the baby's body was discovered covered in rubbish in a bag for life hidden in a disused shed.
Mr Little said at that point Ms Marten gave her first account of what happened but he warned they would hear evidence of her "tendency to lie" to medical professionals.
He said that when she had given birth to her first baby, she had spoken in an Irish accent throughout labour, telling nurses she was from a family of travellers and had grown up in a caravan.
But "she had been raised with a silver spoon, she was a trust fund child", he said.
It was the prosecution's case that the baby's death had been caused by "hypothermia or by smothering and suffocation whilst grossly dangerous co-sleeping".
Both defendants deny the charges and the trial continues.