A new BBC drama explores one of the most vexing acts of sabotage in literary history: the decision by Jane Austen’s sister Cassandra to burn nearly all the writer’s letters after her death. Keeley Hawes and the cast, as well as the series director, talk to Katie Rosseinsky about what might have motivated Cassandra, the perils of being unmarried and female in Regency England and the extraordinary love that existed between the two sisters