An urgent appeal has been released as police believe that a missing newborn baby has been sleeping in a tent in "sub-zero" conditions.
Officers are working to trace Constance Marten, 35, and Mark Gordon, 48, and their newborn baby.
They have established they the family went into Argos on Whitechapel Road at 6.19pm on Saturday, January 7 to buy camping gear.
Mark went in alone and bought two bags of items, paying in cash, including a blue, two-person tent, sleeping bags and two pillows.
He left the shop at 6.40pm.
They then spent just over three hours walking around the Whitechapel Road area and tried to flag down three black cabs, but were refused.
They then left on foot and began walking along Brick Lane towards Bethnal Green at around 10pm on Saturday, January 7.
Police have said that Mark is often seen walking alone ahead of Constance and the baby.
This is the last official sighting of the family.
Anyone who has information on 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. They never ask for personal details and they do not trace your device.
Detective Superintendent Lewis Basford, who is leading the investigation, said: “We are extremely concerned that a newborn baby – less than a week old at the time on 7 January – has been exposed to sub-freezing cold temperatures if Mark and Constance have been camping out somewhere as our evidence suggests.
“No child, especially a tiny, newborn baby, should be forced to endure such dangerous, potentially life-threatening, conditions.
“This is why it is absolutely vital that anyone with information about their whereabouts contacts us as a matter of urgency – whether it is with a recent or older sighting. Every piece of information is crucial to enabling us to find the baby and ensure it is okay.
“My officers will continue working tirelessly behind the scenes to piece together the family’s movements and current whereabouts. It could be that they are trying to blend in with homeless communities, either here in London or further afield, or they could be camping in more rural or wooded areas.
"They could be absolutely anywhere in the country.
"Please keep your eyes peeled, especially while you are out and about in waste ground or beauty spots, or while you’re walking the dog, and report any information, no matter how insignificant you think it is, to us.”
A spokesperson for the Metropolitan Police said: "Detectives are urgently appealing to the public to help them find a newborn baby who they believe has been sleeping in a tent in sub-zero temperatures.
"The team of officers working around the clock to trace Constance Marten, 35, Mark Gordon, 48, and their newborn baby, have established that they went into Argos on Whitechapel Road, E1, at 18:19hrs on Saturday, 7 January to buy camping gear.
"Mark went in alone and bought two big bags full of items, paying in cash, including a blue two-man tent, two sleeping bags and two pillows.
"He left the store at 18:40hrs.
"They then spent slightly more than three hours walking around the Whitechapel Road area. They tried to flag down three black cabs, but were refused.
"They then left the area on foot and were last seen walking along Brick Lane, towards Bethnal Green Road, at 22:01hrs on Saturday, 7 January. Mark is often seen walking alone ahead of Constance and the baby.
"This is the last official sighting of the family."
A spokesperson added: "At 18:33hrs on Thursday, 5 January, officers were called to a car on fire on the hard-shoulder of the M61, near junction four (Farnworth, Bolton).
"However, the occupants were not at the scene.
"It is believed most of their belongings were destroyed in the car fire.
"Enquiries revealed that Constance and Mark were the occupants of the car and that Constance had very recently given birth, possibly one or two days before, and had not been assessed by medical professionals.
"A missing persons investigation was launched by Greater Manchester Police, who established that the family left the vehicle and the motorway safely – walking to the Anchor Lane bridge which links the Highfield and Little Hulton areas.
"Officers believe they then travelled to Liverpool and then onwards to Harwich via a taxi at about 03:30hrs on Friday, 6 January.
"Mark, Constance and a baby were seen by a member of the public in Harwich at about 09:00hrs on Saturday, 7 January.
"Officers also received a number of confirmed sightings of the family in Colchester on Friday, 6 January and Saturday, 7 January.
"Subsequently, the investigation was handed over to Essex Police on Monday, 9 January.
"Essex Police carried out a number of enquiries and reviewed hours of CCTV and were able to place the couple near East Ham Station between 10:30hrs and 12:30hrs on Saturday, 7 January.
"As this was the last confirmed sighting of the family, the investigation was handed over to the Metropolitan Police Service on Thursday, 12 January.
"Detectives have now established that they took a taxi from East Ham, being dropped off in Whitechapel Road at 18:14hrs.
"The couple are seen leaving the taxi with an orange carrier bag and a pram.
"They both have their heads and faces covered and Mark is wearing white plastic bags on his shoes.
"Their movements are then as described above.
"Anyone who has information on 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. They never ask for personal details and they do not trace your device."