On 16–17 May 1943, Royal Airforce Squadron 617 succeeded in Operation Chastise to use bouncing bombs to breach the Möhne and Edersee dams, flooding the Ruhr valley. This very special episode was recorded for the 75th anniversary of the Dambusters raid. Dan talks to Paul Beaver, then Secretary of State for Defence Gavin Williamson MP, and Wing Commander John Butcher, from today's 617 squadron.