Bletchley stars in ITV drama

It was once Britain's best kept secret, now it is a celebrated heritage site which attracts visitors from all over the world.

However, it is not just tourists and history enthusiasts who are keen to explore Bletchley Park near Milton Keynes. The site also regularly attracts writers and film crews who are keen to tell the story of its role in the Second World War.

The Bletchley Cirlce Credit: ITV

ITV recently returned to film the second series of its hit drama, The Bletchley Circle. Olivier award nominated actress Hattie Morahan joins Anna Maxwell Martin, Rachael Stirling, Sophie Rundle and Julie Graham for four new episodes of the codebreaking thriller.

The programme follows the lives of four women, who worked at Bletchley Park during the Second World War. Set a year on from the first series in 1953, the ladies are reunited for their second case when a former colleague is accused of murder.

It's such a multifaceted story. There's the story of the codebreaking, the machines that are involved, but also the people's stories.

The Bletchley Circle is great for that - it's exposing the people because there was a lot of ordinary people doing some quite extraordinary stuff here during the Second World War.

– IAIN STANDEN, Bletchley Park Trust

Most of the series was filmed at Bletchley Park and features scenes in one of the codebreaking huts as well as in the grounds of the historic estate.

The Bletchley Circle will be shown tonight on ITV at 9pm.