More than 1,000 plants were inside.
The Northants Telegraph was at the scene and went inside after officers kicked the doors in.
The plants were across two rooms. Officers surrounded the front of the bingo hall as teams broke into the back of the property. Officers break into the rear with the big red key. The factory had a "sophisticated" hydroponics system. The plants were weeks away from being harvested. Plants in one of the two rooms were on two levels There was still evidence of the venue's former use as a bingo hall inside The bingo hall's carpet had been covered with plastic - including this doodle Wires dangled from the ceiling above the plants The electrical set up in one of the rooms. One officer said it was the biggest factory he had seen. Those running the factory had been making use of the bingo hall's kitchen The plants in the second room. Dozens of sockets were in use in the sophisticated set up