A RAID on a cannabis factory in a disused Cleckheaton lock-up uncovered 250 plants.
Spen police made the find last Thursday at an industrial unit in Tofts Road, where officers found 180 mature cuttings along with a sophisticated growing operation.
Officers filled two large skips with equipment found at the lock-up and spent more than four hours at the scene collecting evidence.
Initial reports said that the value of the Class B drugs was £250,000, however police said the true value was unlikely to be close to that figure.
Police are now investigating who owns the lock-up.
Contact police on 01924 295357 or Crimestoppers on 0800 555111.