Crews from St Neots and Kimbolton were called to Carnaby, in Kimbolton, shortly after 10.45am on Monday. A spokesman for Cambridgeshire Fire and Rescue Service said: A tree stump on the river bank was well alight. Firefighters including in-water trained tethered swimmers used hose reels to extinguish the fire. Crews returned to their station by 12.30pm. An investigation determined that the cause of the fire was accidental.