Sorry cantab, and I hate grouping people and making wide generalizations-- but you brought Britain in the picture, and frankly I hate it when Europeans try to shove their values and concept of what "human decency" is on other cultures and societies.
The act of "helping others" is a great act because it is something you choose to do of your own will.
The act of "not choosing to help others," is frankly not evil. I find the your concept of "moral obligation" ridiculous-- you help others because it is good and so you choose to do so, but simply not choosing to do so, being inactive, is not wrong.
What is wrong is thinking you have the right to tell people that they have an "obligation to help others," when helping others is something you do out of voluntary good will.