Arsonists are believed to be behind yet another fire at a derelict school, which has gone up in flames four times in less than a year. Firefighters were called to the former St John Fisher Catholic School building in Ordnance Street, Chatham, just after 12.30pm today (Sunday). Five fire engines and a height vehicle attended and crews used hose reel jets to douse the flames. A spokesperson said: “There were no reported injuries and the cause is not yet known but is being treated as suspicious.” It comes just days after another fire took hold at the site. Crews were called to battle the blaze at…