Helen Mark visits Coleshill in Oxfordshire to learn about its wartime secrets. In 1940, with fear growing that Britain could be invaded by the German army, the estate became the training headquarters for a secret underground army. Over the next four years, thousands of country men - such as farmers, gamekeepers and foresters - were trained in underground resistance. They lived outwardly ordinary lives, but their job was to spring into action in the event of invasion, disappearing into bunkers buried in the landscape and emerging to disrupt the invading army through sabotage and hand-to-hand combat. Their life expectancy would have been around two weeks. With its quiet countryside location, far from military targets but near good transport links to London, Coleshill was the perfect place for this top-secret training base. High walls around the estate also kept its activities shielded from prying eyes. Even after the war the cloak of secrecy persisted, and today most people have never heard of the role Coleshill played in Britain's wartime history. Helen climbs down into a replica of the original underground operational base, used for training recruits, and finds out what life would have been like for these 'Auxiliary Units' or 'Auxiliers', as they were known. Sworn to secrecy, many never spoke of their experiences and took their knowledge with them to the grave. The feared German invasion never happened, so their services were not called on for real, and in many cases even their families never knew what the Auxiliers had signed up for. Now many people are piecing together their family histories and are keen to find out whether their fathers, grandfathers or uncles may have been part of one of the best-kept secrets of World War II. Produced by Emma Campbell

The landscape of south Wales has been shaped and defined by coal. In this programme, Helen Mark explores the Rhondda valley – finding out about is history and asking what its future may look like, now the heavy industry has gone. She visits a disused railway tunnel which once carried coal from the mines to the port of Swansea, but which has been closed and sealed off for decades. Now a group of enthusiasts is campaigning to re-open the tunnel as a tourist attraction. They have ambitions plans for it to become the longest cycling tunnel in Europe, with hopes that it could also function as an exhibition space, miniature concert hall and even a wedding venue. Helen puts on her safety helmet and is lowered down through a shaft into the tunnel, to see for herself how the structures of the past could take on a new life in the future. Produced by Emma Campbell

Jamie Allan was a celebrated musician and friend of the aristocracy, but also a thief, bigamist, and deserter. Known as "The Dukes Piper", he is the source of many songs and legends in Northumbria. In this programme, folk singer Jez Lowe traces one of these legends across the Rivers Ouse and Nidd, over which Jamie Allan supposedly fled from army conscription to freedom in Scotland. As he crosses the waterways of North Yorkshire, Jez finds out about the life and adventures of this Robin Hood figure from the 18th century, and enjoys some of the music he would have played. Produced by Helen Lennard

Ian Marchant is time-travelling through Herefordshire’s Golden Valley in springtime. He learns about "the wine of the west" in cider-maker Denis Gwatkin’s orchards, discovers Herefordshire’s lost castle at Snodhill, and visits an Elizabethan watermeadow system in Turnastone. Ian finds out why modern-day pilgrims are walking through the Golden Valley. High above it, he visits ancient Arthur’s Stone which captured the imagination of CS Lewis. Win Scutt from English Heritage tells Ian of exciting archaeological discoveries about the dolmen, built by Neolithic cattle herders. Producer: Sarah Swading

Norfolk has around two hundred abandoned villages and more ruined churches than any other county. In this programme, Lawrence D'Silva explores some of them and finds out why there are so many in Norfolk's rural landscapes. He wanders through the grassy outlines of the streets which once made up the medieval village of Godwick, imagines what used to exist in its ghostly outlines, and learns what led to its decline. He finds out how some deserted landscapes are now havens for wildlife, and experiences thousands of rooks and crows coming down to roost at dusk in Buckenham. At East Somerton he finds a ruined church almost swallowed up by the surrounding woodland and hears about the legend of the tree now growing right in the middle of what was once the church's nave. There's even a ruined church which is now part of a private garden. Lawrence meets its owners and finds out how part of Norfolk's history has become part of their everyday lives. Produced by Emma Campbell