Highly organised criminal gangs have been targeting unsuspecting landlords and reaping the profits from a network of cannabis factories in the county.
Nearly 20 raids this year – the latest taking place at a semi-detatched home in rural Great Houghton yesterday – have been linked by police to as few as three London-based gangs.
A warning has now been issued to landlords to check their properties for suspicious activity, to help Northamptonshire Police's organised crime unit track down the people responsible for the lucrative operations.
The landlord of the house at the centre of the latest find, in Great Houghton, who asked not to be named, described being duped by a drugs baron, who presented himself as a respectable family man.
He said: "He told me his partner was expecting, and that he wanted a nice quiet place for them to raise a baby. I had absolutely no idea.
"I was trembling when the police called, and I still am now. I've never seen anything like it and I'm shocked at what they've done to the house.
"The amount of damage they've caused with the lighting equipment and the electrics is more than I could have imagined."
About 170 cannabis plants were uncovered at the three-bedroom home yesterday in a factory which police suspect had been up and running since September. It was capable of producing a crop of plants worth in the region of £100,000 every 10 weeks.
Det Con Gary Fowler, of the organised crime unit, said: "Landlords are key to helping us find the people responsible for cannabis factories.
"We know people have been specifically targeting Northamptonshire, and other shire counties, and taking out long-term leases. Often they will present themselves as families and will be very convincing, and they will usually be driving very nice cars.
"We want landlords to do regular checks on their properties and be aware of suspicious tenants."
The latest raid took place at about 9.30am yesterday in Willow Lane, Great Houghton. Det Con Kelvin Leaton, of the reducing the supply team, said: "This one has obviously been here a while and has probably turned over two or three crops in that time.
"These factories are worth hundreds of thousands of pounds and we need the help of the community to find them."