Panorama returns to the scene of the killing of 30 British tourists by a gunman on the beach at Sousse in June 2015. Reporter Jane Corbin investigates whether security concerns were ignored before the attack and if lives could have been saved on the day. She asks why there wasn't tighter security or a warning to holidaymakers to stay away from Tunisia after similar attacks. And should the Tunisian government, the British tour operators and the Foreign Office bear any responsibility for what happened?