Warsaw has just moved closer to Munich, Berlin nudged towards Paris, and Aachen slipped nearer to Salzburg. These are just three examples of city pairs that are newly linked, as of this week, by direct night trains. None of these city pairs currently has direct daytime trains, so the overnight options create a web of opportunities. As always in December, rail operators across Europe are introducing new schedules, along the way creating tantalising links where none existed before.