I found this article from the WSJ helpful. It features Bishop Welby's business background, which is an important feature in coming to a fuller picture of this truly fine Christian man.
I am bit more optimistic of the free market system producing capital as long as it stays accountable to a strong rule of law that inhibits fraud. But I find his "rational choice" theory about markets very Christian. Rationality is always relative to a bigger story of what is real, good and true. People are more motivated by self-interest (not rationality), which would be okay if we were all saints. And, of course, we are not. Thus, the need for a strong rule of law to curb greed, fraud, etc.