Horses for Courses
Everyone posting is right on this one in one way or another - horses for courses indeed.
In our family, we make around 20 FR flights out of GRN a year and 6 TGV trips.
Paris always by TGV, more comfortable. (Couldn't be less than FR could it !)
London by FR, faster/cheaper. Always back via Perpignan as GRN is an appalling inefficient place to land.
Madrid also by FR as the RENFE website for the AVE - Spanish version of the TGV - is a disaster area and I've never yet succeeded in booking tickets on it.
And I do drive to Perpignan to book train tickets as I get special deals that way, and also stop at Auchan on the way back for cheese, meat, fish and vegetables.
And one poster said it all: until one can book on a single ticket a train ride from (say) Perpignan or Marseille or Montpellier - to London direct - FR and easyJet will have it their way. At the moment it's one cheap TGV ticket to Paris or Lille and one expensive Eurostar from there to London. Completely crazy ! One Europe ? Don't make me laugh.