I've checked the costs of first class travel by high speed train in France and to UK. According to pictures, first class seats in the Eurostar and TGV look similar in terms of legroom and width, while fares are not. I am not a business traveler but a tourist looking for extra comfort.
I did a comparison of full-fare ticket prices on two trips that are similar in distance and travel time.
For instance, a trip from Paris to Lyon, which lasts 2 hours and covers 500km, costs about €100 full-fare in first class. Using the Eurostar between Paris and London, for a trip that is about the same length and duration, full fare in Standard Premier class is about €200.
Eurostar first class is far more expensive than TGV first class. Does the Eurostar first class offer services that are worth the extra cost?