Constance Marten, Mark Gordon and their newborn child were last seen at East Ham station in Newham, east London, on the evening of January 7.

Detectives from Essex Police established the trio took a taxi from Harwich to East Ham station that day.

Unknown whereabouts - Constance Marten (Image: Greater Manchester Police)

The force said there had been confirmed sightings of them in Colchester on the same day.

Ms Marten and Mr Gordon were initially travelling in a vehicle that was found broken down in on the M61 at Bolton, Lancashire.

Officers from the Metropolitan Police have taken over the investigation into their whereabouts and are making “urgent inquiries” to find them.

Missing - Mark Gordon (Image: Greater Manchester Police)

Police said 35-year-old Ms Marten is believed to have “very recently” given birth, adding that “neither she nor the baby have been assessed by medical professionals”.

Detective Superintendent Lewis Basford made a direct plea to the couple to make contact with officers.

He said: “Constance and Mark, I appeal directly to you, please think of your baby’s health and wellbeing, and get in touch with us so we can ensure your child is medically well and has no underlying issues.”