A baby found in the search for the missing newborn of Constance Marten and Mark Gordon could have been dead ‘for some time’, police have said.

The couple was arrested in Brighton on Monday night.

They were detained on suspicion of child neglect and remain in police custody after nearly two months on the run.

Police confirmed they had found the body of an infant on Wednesday evening.

In a press conference today, police said formal identification had not yet been carried out.

But they added they feared the baby found may have been ‘dead for quite some time’.

No gender has been confirmed for the baby found.

Detective Superintendent Lewis Basford said: ‘At this stage we have not yet been able to confirm the baby’s gender and post-mortem examination has not yet taken place.

‘Despite this, based on our inquiries we’ve carried out so far, we believe sadly the baby may have been dead for some time before they were found.

‘It is too early for us to provide a more specific date.

‘Because we believe the death occurred during the course of a missing person investigation we have made a mandatory referral to the Independent Office for Police Conduct (IOPC). This is standard protocol for such circumstances.’

Police at the cordoned off scene in woodland close to Brentwood Crescent in Brighton (Picture: PA)

Constance Marten and Mark Gordon were arrested on Monday night (Picture: AP)

A map of the couple’s movements in January (Picture: Metro.co.uk)

Teams had led a desperate search to scour a large area between Brighton and Newhaven to try to find their baby, which had not had any medical attention since birth in early January.

Helicopters, sniffer dogs, thermal imaging cameras and drones were all used in the search.

An investigation was launched when the couple vanished on January 5, after their child was born in a car in Bolton.

Their vehicle was found abandoned and on fire at the edge of the M61.

The pair managed to evade police for 54 days, paying for everything in cash and covering their faces when on CCTV.

Mark Gordon and Constance Marten spotted on Whitechapel Road in London (Picture: PA)

Police search teams in Roedale Valley Allotments, Brighton (Picture: PA)

They moved around the country, paying for everything in cash and covering their faces when on CCTV.

But a tip-off led to them being detained at around 9.30pm on Monday by officers from Sussex Police in Stanmer Villas.

CCTV footage had showed Marten and Gordon walking past a row of houses in Brighton, both with their hoods up, prior to their arrest.

Marten comes from an aristocratic family with royal connections.

On Tuesday her father, Napier Marten, expressed his immense relief that she had been found, but said he remained alarmed that the baby was missing.

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Police said formal identification had not yet been carried out.