Wallabie - I'll have a go.
There are many jobs within the airline industry which carry as much financial risk as the Captain does, but with less pay and training. However there are very few jobs that carry as much responsibility for human life as that of the Captain, and of those that do, only the flight crew will live or die as a result of their actions. Anybody who is not on board the aircraft can choose to walk away from a problem, or take time to think about it. It may be detrimental to their career, but the option is there. Those on board the aircraft do not have the first option, and the latter is often in very short supply. In those short moments they will preserve the airlines priceless reputation for safety, or they may cause financial disaster far greater than any single decision taken in an office. Therefore, the Captain deserves to be paid more.
Bahrain lad-
If BA could robustly crew day trips on Concorde they'd have done it a long time ago.
Charter guys do indeed fly 13 hour days, as do many long haul pilots. But which aircraft do you think is most demanding to fly - a glass cockpit 757 doing M0.78, or a clockwork, 3 crew, 4 engine supersonic M2.0 sixties jet?
Finally, due to the seniority of the fleet, I think you'll find that most crew on the SST take a very hefty pay cut to fly it. Most do it for love (yes there are people in BA who enjoy flying), and a few do it for prestige.