Re: 1st class flights
I can see them doing that, but his point was he had to go to China to do the work - that was where it had to be done, so it was an expense anyway. He worked for a very large French based multinational, and they sent people all over the world all the time on fancy flights and put them up in fancy hotels and not that I would say it, paid bribes everywhere and claimed those as expenses too...
The French tax authorities are probably as sneaky/nasty/competent as the UK ones, but I know he got away with it for a year and was very nervous about a random tax bill from the Republic who never chased him up. Plus it was a few years ago when travel budgets were a lot more generous than today... I flown super-economy - and bring your own sandwiches if I need to travel...