Well the proof is in my Google track (207.5km)... also in my pre-google days, a string measurement on the maps gave about 200km which you can probably add a little to for kinks in paths which strings tend to miss ;-)
Of course when TWA finish we shall have their track! But that will contain several hundred metres of distance travelled whilst they were stopped and the GPS was jumping about a bit. Should be able to remove that I guess.
On our attempt, my GPS gave a reading of 100km up to Champagne Castle which is way more than the measurement I have of 80km. I've had big overreads with handheld GPS before though. Maybe got something to do with arm swinging as well?