A S/H Captain with Ezy or BA will earn ballpark 100k a year. Some will earn a fair amount more with bonuses/allowances. So you are looking at roughly twice what a Virgin Trains driver brings in. For a closer comparison, an F/O in their first few years at BA (direct entry salary) earns around 60-65k with potential to boost that with overtime.
I too have a few friends working for the railways and it seems a VT driver position is seen as something of a career aspiration as they are towards the top end of the pay scale along with Eurostar drivers. These guys are working alone for hours on end and in charge of a train travelling at speeds of well over 100mph that will carry hundreds of people long distances - I would say that is a reasonable amount of responsibility for what they earn, but just as with airline pilot salaries, the accountants have other ideas. The testing and training of drivers has a very high failure rate and there is a lot more to the job than public perception would have you believe - sound familiar pilots?