Interesting you tube video.
https://www.youtube.com/watch?v=UQYCtHln9w0
Note how many transfers were needed to go as far as Warsaw.
FYI, London to Warsaw is highway ???? kilometers.
1645 km or 1022 miles
Some math follows: 1023 / 24 = 42.67 mph average.
And that was using Eurostar from London to Brussels, and then ICE to Cologne.