Neighbours had joked about living next-door to a drugs factory months before the property in Spencer Bridge Road, Spencer, was eventually raided on Friday.

A team of seven officers found about 600 plants in four rooms at the rented terrace house during the 8am swoop. A 42-year-old man was arrested in connection with drugs offences and was interviewed last night at Campbell Square police station.

The mains electricity had been bypassed and a sophisticated drugs manufacturing plant had been created, with growing equipment including high-powered lights and air vents.

Officers said they had to check for "booby traps" as they entered the house.

Pc Matthew Mustoe, who took part in the operation, said the raid was an example of the police working with the community.

He said: "Drugs are one of our priorities on the Spencer safer community team. We have conducted this warrant on community intelligence and found this drugs factory.

"We advise people to call us if they see any suspicious activity."

Spencer safer community team Sgt Dan Finney added: "This is a great result for the safer community team and local residents."

The property is now being made safe before the plants, worth between £150,000 and £200,000, are taken away and the scene examined by forensic officers.

A neighbour, who asked to remain anonymous, said: "Our daughter said 'I reckon there is a cannabis factory next door' as a joke because we never see anybody.

"When they first moved in there was loud music late at night during the first week.

"It's unbelievable to think that it happened here, but then if you think about it the road is perfect for a cannabis factory because it's busy."

The family also noticed bright lights, a sign of a cannabis factory, at the back of the house and heard banging noises as well as the sounds of people tampering with the sockets.

Cannabis factories are now found regularly by Northamptonshire Police – at one stage last year, officers were raiding three a month.

Between April and November 2007, a total of 23 houses were found to have been converted into hi-tech hydroponics factories capable of producing the class C drug.

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