By Renee Maltezou and Kate Holton ATHENS/LONDON (Reuters) – Emergency services battled wildfires across swathes of southern Europe amid mass evacuations on Wednesday, as warnings sounded in London after Britain’s hottest day that the fight against climate change needed to be stepped up. Hundreds fled in central Italy as gas tanks exploded in a forest fire near the Tuscan town of Lucca. Similar numbers fled in Greece as a blaze fuelled by gale-force winds raged in mountains north of Athens. Greek authorities said later in the day that the blaze had been tamed. A brutal heatwave with spikes well…