LONDON (Reuters) – Firefighters worked through the night to damp down wildfires and engineers raced on Wednesday to fix train tracks that buckled in the heat as Britain woke up to the aftermath of its hottest ever day. The London Fire Brigade endured its busiest day since World War Two on Tuesday when temperatures topped 40C for the first time, igniting fires that destroyed dozens of properties in the capital and sent flames racing through tinderbox-dry grassland at the sides of railway tracks and roads. Trains running from London up the east coast of England were cancelled at least until midd…