British police have been slammed for holding a married couple without charge over the Gatwick chaos -- before admitting "there may never have been a drone".

Paul Gait, 47, and wife Elaine Kirk, 54, spent more than 36 hours being quizzed by police over the device that brought Gatwick Airport to its knees, reports The Sun.

They were arrested at their home close to the airport on Friday night over the attacks -- with Gatwick now offering a $A90,000 reward for the real culprit.

But police confirmed they are no longer suspects and said a "damaged drone" was found near "the north perimeter" of Gatwick would be taken away for investigation.

He told the BBC it was a "working assumption" that the device was connected to their investigation but that police were keeping "an open mind".

"We are meticulously going through that information to see if that produces any other further lines of inquiry, and also where we may focus our efforts in terms of house-to-house inquiries, CCTV footage, and any other information that will help us work through this investigation."

He said there was no footage of the drones and police were relying on witness accounts.

He added there was "always a possibility that there may not have been any genuine drone activity in the first place", but they were working on a range of information from members of the public, police officers and staff working at Gatwick who had reported otherwise.

Of the "damaged drone", Detective Chief Superintendent Tingley said: "Obviously we will be doing everything we can with regards to forensically examining that drone and that is something that is being fast-tracked and expedited."

Police said Ms Kirk and Mr Gait had co-operated fully with police and were released without charge.

"Both people have fully co-operated with our inquiries and I am satisfied that they are no longer suspects in the drone incidents at Gatwick," Detective Chief Superintendent Tingley said in a statement.

Ms Kirk and Mr Gait were arrested on Friday in connection with the drone invasion that had shut down the UK’s second-busiest airport.

A house in Crawley -- about eight kilometres from the airport -- was then searched on Saturday.

However, Mr Gait’s boss told The Telegraph how the window fitter and drone enthusiast was working when the attacks took place.

John Allard, who runs Allard Double Glazing, told the newspaper: "Paul normally comes in around 7.45am and I remember on those days he then worked late on site on a fitting job.

"I don’t think it can be him. He was busy on site working when it was happening."

He also said Ms Kirk had "no interest" in flying drones -- but said Mr Gait had used the machines in the past.

Locals also told how Mr Gait had been spotted with a remote-controlled model helicopter in the area.

One said: "I saw him flying a helicopter, it was remote controlled. That was a few years ago and he recently said to me, ’I’ve given all that up now’."

Another revealed Mr Gait had a remote-controlled car and a helicopter, adding: "I remember thinking ’look at that big kid with his toys!’"

There had been speculation the people behind the drone attack were "ecowarriors" possibly protesting the airport expansion.

Check-in lines at Gatwick stretched the length of the departures hall as harried travellers tried to make good on Christmas plans up-ended by three days of extended shutdowns caused by drones being spotted over the airfield.

The persistent drone crisis at Gatwick, 45 kilometres south of London, has had a ripple effect throughout the international air travel system since Wednesday night, when the first drone was spotted.

Passengers Relieved as Flights Resume at Gatwick Airport

A Gatwick spokesman said on Saturday that "things are going in the right direction" and should be back to normal by the end of the weekend after a horrendous few days that saw tens of thousands of travellers stranded or delayed.

Police say the investigation is ongoing and the military was still deployed to prevent further drone incursions from shutting Gatwick’s airspace.

British police have not said if they think the two suspects acted alone or as part of a larger group.

The motive for their aggressive drone flights has not been established, but officials say there are no indications it is "terror related."

There have been no new drone sightings since the arrests. Gatwick’s arrival and departure boards showed that most flights operated Saturday but there were still a significant number of delayed takeoffs and landings.

In all, the airport hoped to run 757 flights, serving just under 125,000 passengers.

Still, Gatwick authorities urged passengers to check the status of their flights Saturday with their airlines before heading to the airport, which handles 43 million passengers a year.

"Passengers should expect some delays and cancellations as we continue to recover our operations following three days of disruption," a Gatwick spokesman said.

New drone sightings Friday evening caused fresh problems for holiday travellers at Gatwick, which had just reopened in the morning after a 36-hour shutdown. Authorities then had to hastily suspend flights for more than an hour Friday afternoon on one of the busiest travel days of the year.

Officials said extra military capabilities allowed flights to resume Friday night after the 70-minute halt but did not say what equipment had been put in place to counteract the drones.

"Our investigations are still ongoing, and our activities at the airport continue to build resilience to detect and mitigate further incursions from drones," said Superintendent James Collis, who urged the public to contact authorities immediately if they had any relevant information about the drones.

Hundreds of people had to sleep at Gatwick on Thursday night, and many noted how freezing and uncomfortable it was.

Officials said Saturday they are keeping the airport’s two main terminals heated.