Since the client on the Paris thing for some reason declined to spend $9,000 per person for us to fly business class, I decided to take American 90 to London and then take Eurostar under the Channel. The strategy worked; I got sleep on a real bed Sunday night, and was coherent and lucid Monday afternoon at the job site.
This time, I put a clock on the train. Here's what my phone GPS showed about 30 minutes outside London:
The screen shot above (click for full size) shows that about here the train was moving 281 km/h, which is how it gets from London to Paris with two stops in under two and a half hours. Flying from London City to Orly would take about that long, and I'd still have had to take the RER up to the job site. At one point I clocked it at 297 km/h, which is still not the fastest train in France. SNCF's TGV-320 goes—wait for it—320 km/h. (Then there's the Shanghai Maglev...)
This is why I love Europe.