The key cast for drama series “Hamburg Days,” about The Beatles ’ early days in the German city, has been revealed as the six-parter started filming in Hamburg, Munich and Liverpool. The series stars Rhys Mannion (“It Is in Us All,” “Freud’s Last Session”) as John Lennon, Liverpudlian singer/songwriter Ellis Murphy as Paul McCartney, newcomer Harvey Brett as George Harrison, Louis Landau (“Rivals,” “Kennedy”) as Stu Sutcliffe, newcomer Patrick Gilmore as Pete Best, Luna Jordan (“Wild Republic,” “Sleeping Dog”) as Astrid Kirchherr, Casper von Bülow (“Druck,” “Wann wird es endlich wieder so, wie es nie war”) as Klaus Voorman, Laura Tonke (“22 Lengths,” “Amrum”) as Nielsa Kirchherr, Trystan Pütter (“Ku’damm 56”), and Max von der Groeben (“Fack Ju Göhte”).…