Where the Common Law fears to tread

" Between at least the early part of the 20th century and about 1990, it had been generally understood that there was no right of recovery in restitution of money paid pursuant to an ultra vires demand by a public authority. This state of the law was overturned by the House of Lords in the great case of Woolwich Building Society v Inland Revenue Commissioners [1992] 3 WLR 366. One argument advanced against the recognition of such a principle was that to do so would overstep the boundary that we traditionally set for ourselves, separating the legitimate development of the law from legislation..."