FGW = First Great Western, or Worst Great Western as they're more commonly known...

Overcrowded, high prices, delays, one of the stingiest delay compensation policies of any UK long distance train operator, customer services who cut and paste random bits into replies which don't actually answer the question, and who deny compensation that ought to be due. By UK standards they're not great but not the worst, compared to Eurostar they're terrible

Oh, and now they're suffering a load of strikes because they've ordered some new trains without proper catering facilities (for journeys which can be hours long), without discussing it with their staff and especially not with their staff who operate the catering facilities...

Their lounge in Paddington isn't a patch on the Eurostar ones in London or Paris either!