You might think the blue-collar town of Lens, in the heart of northern France’s historic mining region, would make for an unlikely city break, the area having fallen on hard times following the closure of its pits and the loss of its defining industry. But, as reporter Rhys Griffiths discovered on a recent trip, the town and its surrounding countryside – all little more than an hour’s drive from the Channel ports – have much to offer the visitor, from incredible art to a story rich with wartime and industrial heritage… Standing at one end of the Gallery of Time, the centrepiece of the Louvre-L…