I do not know the original source for the claim that Mill was the source for Hayek's view. Hayek definitely had very mixed views about Mill, for unsurprising reasons. One sign of his respect is that when he married his second wife, they followed for their honeymoon exactly one century later to the day, day by day, the path that Mill and Harriett took in Greece and Turkey. This is from Bruce Caldwell. Barkley Rosser