The idea of the IWF was basically taken from the U.S. where the Republicans created a nominally independent but hardly independent "charity" to circumvent the law.
That said though, maybe it still affords someone a measure of psychological security, when you consider what the Tory Government has been up to for the past few years.
It always made more sense in the U.S. though, because the U.S. actually has meaningful restrictions on the federal government.