大象传媒

It was a repressive regime that brutally enforced the idea of secrecy throughout the Cold War.

Yet for decades, the 大象传媒 managed to give listeners in East Germany a link to the outside world through a programme called 'Letters Without Signature'.

The people who wrote to it were putting themselves in grave danger, but hundreds took the risk of being prosecuted for treason to make sure their letters made it through to the show.

So why did they do it - and what was the truth behind the mysterious 'Austin Harrison' who hosted the programme?

Dr Emily Oliver has been finding out more for a documentary you can watch right now on the iPlayer.

She's been talking to our weekend presenter Jack Murley.