20 However, the existence of difficulties and hurdles does not mean a proceeding is foredoomed to fail, in the sense that it is hopeless. Mr Knight's contention is that there is long established authority for the contention that a public authority may only impose a financial burden if expressly and unambiguously empowered to do so by the legislature. In particular, he relies upon statements to that effect in the following cases: AttorneyGeneral v Wilts United Dairies Ltd,[8] Marsh v Shiare of SerpentineHarrandale,[9] Carbines v Powell,[10] Commonwealth and anor v The Colonial Combing, Spinning and Weaving Co Ltd,[11] and Congreve v Home Office.[12] Given that s 21(1) is expressed in general terms, and no other section of the Act expressly empowers the Secretary or a prison governor to impose surcharges or levies on items sold to prisoners from prison canteens, he submits that the Secretary and her predecessor have acted beyond power in deciding to impose, and in continuing to impose the levy.