A fire at an industrial premises is being treated as suspected arson. Crews spent just less than three hours battling the blaze at the industrial premises in Hockenden Lane, Swanley last night. It is unknown how the fire started but the Kent Fire and Rescue Service say the cause is “being treated as suspicious”. Its crews were called just before 11.20pm and were at the site until around 2.10am. Five fire engines were sent to the scene including two from London Fire Brigade, as well as a bulk water unit. Wearing breathing apparatus the firefighters extinguished the blaze using hose reel jets. N…