Detectives are offering a £10,000 reward for information that helps them find a missing couple and their newborn baby.
Police say they are “extremely concerned” about Mark Gordon and Constance Marten, who went missing after their car broke down in Bolton on 5 January.
Detectives say their baby has been exposed to sub-zero temperatures for almost a month and the couple were “constantly moving and awake for at least a few days” after the birth.
The couple were last seen in Newhaven, East Sussex, on 8 January carrying bags containing a two-man tent, sleeping bags and pillows that they had purchased from Argos the evening before.
The previous night they dumped a pushchair in Spitalfields, east London.
Police say the couple could still be camping somewhere in the UK.
Ms Marten, 35, who is from a wealthy family with connections to the royals, has lived an isolated life with Mr Gordon, a 48-year-old convicted sex offender, since they met in 2016.
Neither they nor their newborn have had any medical attention since they went missing.
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Father’s plea to missing daughter
Detective Superintendent Lewis Basford, who is leading the investigation, said: “We continue to be extremely concerned about the health and wellbeing of the newborn baby, which has had no medical care and has been on the move, and possibly exposed to sub-zero temperatures, for almost a month now.
“We’re also concerned for the welfare of Constance and Mark because our enquiries suggest that they were constantly moving and awake for at least a few days – which must be especially draining on someone who had recently given birth with no medical attention.
“Finding the baby is our top priority and we are now offering a £10,000 reward to anyone who provides information which leads to them being found.”