Pembrokeshire is to feature again tonight (Tuesday) in BBC Four's Hidden Histories.

The BAFTA Cymru nominated series follows the everyday investigative work of the Aberystwyth-based Royal Commission on the Ancient and Historical Monuments of Wales.

Tonight's episode, which airs at 7.30pm, reveals the World War One secrets hidden in Pembrokeshire's cliffs The programme sees the commission’s Toby Driver flying into the past, on a mission to photograph strange shapes in the Pembrokeshire landscape.

The unusual forms were key elements in a military operation where, nearly a century ago, young British soldiers trained before leaving for the Western Front.

The commission’s military expert, Medwyn Parry, looks into the army training camp at Penally, which has been there since 1873.

Also featured in the programme is an architectural treasure trove of a house near Raglan, Monmouthshire and Anglesey's Parys Mountain copper mine, the largest in the world during the last half of the 18th century.