Eurostar to Brussels, then a high-speed train to Cologne
Best for most- Eurostar: London St Pancras to Brussels-MidiAbout 1h 55m. You check in and go through passport control at St Pancras, so allow time before departure.
- Brussels-Midi to Köln HauptbahnhofAbout 1h 50m by Deutsche Bahn ICE or Eurostar (the former Thalys trains), with no change of station in Brussels. You can book both legs in one booking on eurostar.com, and if a delay makes you miss your connection, you'll be put on the next train.
Advance fares start at roughly £50 each way for the Eurostar and about €19 for the ICE, but December weekends sell out, so book as soon as your dates are set.