100 years after it happened, Kate Humble and Andy Torbet try to piece together the events of 21st November 1916, when the Britannic, sister ship to the Titanic, sank in just 55 minutes. Kate speaks to descendants of some of the survivors, including Violet Jessops, who survived both Titanic and Britannic, and look-out Archie Jewell, who miraculously survived when those around him lost their lives.