And the Channel between England and France is a mere 20 miles at its narrowest point, Ireland is 12 (the UK's nearest EU neighbors). You can argue it down to zero miles for Ireland if you start your journey in Northern Ireland.
The sun absolutely does set on what little is left of the "British Empire" in the 21st century.
The famous phrase was as much about the relative geo-political strength of the empire in the 18th and 19th centuries as much as it has to do with actually being able to see a sunset... but feel free to take it literally if you like.
The sun never sets.....