Writer Sally Wainwright looks back on the origins of her Bafta-winning drama Happy Valley, which first appeared on the nation’s TV screens in 2014, and instantly established itself as one of the great television experiences of recent years. With a cast led by Sarah Lancashire, James Norton and Siobhan Finneran, it was a case of characters, crime and countryside all combining beautifully to create unmissable television, that has continued to hook millions of viewers. Here, Sally reveals just how happy those early days of Happy Valley really were - sharing the inside story of how the show first came together, the challenges faced in those early days and the pressures of living up to expectations once the series had established itself as an acclaimed success.