£1.9 million is only under 4% of his wealth.... its really not actually that much percentage wise although it seems like a lot when you consider the figures.. I wonder if there would be as much media hysteria about this if she he was worth £57000 and she was asking for 1.9 grand... probably not.
I do not know the full ins and outs of the case, but based on what I have read. If he did indeed shirk his responsibilities and did not care for or pay towards his child for the duration of his child's childhood, then I don't think requesting under 4% of his wealth is actually all that unreasonable.
It is not just a case of child support payments owned, its about the impact that may or may not have had on her ability to develop a career of her own whilst caring single handedly for the child he also created, its about cost of childcare costs to persue a career of her own whilst being a single mum... there are lots of factors to consider here.