Detectives issued an urgent appeal to find the newborn aristocrat, who, according to them, was sleeping in a tent in sub-zero temperatures.
Constance Martin35 years old, living off the grid after eloping more than two weeks ago with one-day-old baby and partner Mark Gordon48 years old, who served 20 years in an American prison for rape and beatings.
Officers fear for the baby’s safety in -3C temperatures and because they have not received medical attention since the birth in early January.
Gordon went into the store alone and bought two large bags filled with items, paying cash, including a blue two-person tent, two sleeping bags and two pillows. After about 20 minutes, he left the store.
He and Ms Marten then spent just over three hours walking around the Whitechapel Road area. They tried to stop three black taxis, but were refused.
The pair then left the area on foot and were last seen walking Brick street, in the direction of Bethnal Green Road, around 10 p.m. Gordon is often seen walking alone ahead of Ms. Marten and the baby.
The Metropolitan police said this was the last official sighting of the family.
Detective Constable Lewis Basford, who is leading the investigation, said: “We are extremely concerned that the newborn baby, who was less than a week old at the time on January 7, was exposed to the freezing temperatures when Mark and Constance were exposed to the freezing temperatures. camping somewhere, as evidenced by our data.
“No child, especially a tiny, newborn, should be forced to endure such dangerous, potentially life-threatening, conditions.
“That is why it is vital that anyone with information about their whereabouts contact us urgently – whether it was recently or previously. Every bit of information is crucial to us being able to find the child and make sure they are okay.
“My officers will continue to work tirelessly behind the scenes to piece together the family’s movements and current whereabouts. They may be trying to blend in with homeless communities here in London or further afield, or they may be camping in a more rural or wooded area.
“They can be absolutely anywhere in the country. Please keep your eyes open, especially when you’re out in wasteland or beautiful places, or when you’re walking your dog, and let us know any information, no matter how trivial it seems to you.’
Gordon’s conviction stems from an assault in Florida on a woman in her 20s when he was 14.
Police made a number of appeals after the couple’s car caught fire on the M61 near Bolton on January 5 as they traveled to Liverpool, Harwich in Essex and Colchester.
They were seen at East Ham station in Newham January 7 from 11.45 to 12.30.
Ms Maarten’s father Napier Maarten, a former page to the late Queen whose grandfather was the 3rd Baron Allington, made an emotional plea for her safe return last week.
She grew up at Critchell House, a Dorset estate, and her grandmother was a friend of Princess Margaret.
Ms Marten was a promising drama student until she met Gordon in 2016. Since then, the couple led an isolated life, cut off from family and friends.
Starting around September of last year, they began living in a series of AirBnBs around the country for short-term rentals and saved up a significant amount of money so they could live off the grid and avoid the attention of the authorities.
After the disappearance, whenever they were seen on CCTV, their faces were covered and the baby was hidden from view, although the taxi drivers the couple used could hear the baby’s noises.
Anyone with information about the family’s whereabouts should call the incident room on 020 7175 0785.
Alternatively, information can be reported 100 per cent anonymously to the independent charity Crimestoppers on 0800 555 111.