The Metropolitan Police have joined forces with Sussex Police as they begin a mass manhunt in the county to track down the missing baby of aristocrat Constance Marten. Helicopters, drones and specialist search officers have taken to the open land in Sussex by police to locate the baby. Marten and her partner Mark Gordon were found on Monday, February 27, 54 days after they first went on the run from the authorities. The pair were spotted by a member of the public in Stanmer Villas, Brighton, shortly after 9.30pm. Police say the baby they were with is still missing and an urgent search operation is taking place in the area. HAVE YOU READ THIS? IN PICTURES: Manhunt under way to find Constance Marten's missing baby Detective Superintendent Lewis Basford from the Metropolitan Police said: “We are asking the public to remain vigilant in the open areas and when they go about their business. "Also to look at the premises they own and the out-buildings that may be within their own property. Please take five minutes to look at those and assist us in the search for the baby.” Anyone with information on the baby’s whereabouts is asked to call 999 - quoting operation zeal. It has been more than two months since the couple’s car was found burning on the M61 in Bolton, Greater Manchester, on January 5. Marten, Gordon and the baby had believed to have been travelling around the UK ever since. On February 6, Police offered a £10,000 reward to anyone with information on the group of three, after they had been traced to Newhaven and believed to be camping the Sussex countryside.