that class will be changing from time to time; and until the charge crystallises and attaches to the assets, the chargor may carry on its business in the ordinary way. When conducting a recent review of the authorities, the House of Lords brought some clarity to this area of law in National Westminster bank plc v Spectrum Plus Ltd [2005] UKHL 41. The essential test of whether a charge was a fixed charge related to the chargor's power to continue to deal with the asset. In order to preserve the status of a charge as a fixed one, the bank must exercise actual control over disposal of the asset. If the chargor is able to deal with the asset, such as by drawing from the account in which charged funds are kept, or into which the proceeds of trade receivables are deposited, then the holder of the charge does not have effective control. They said: "the asset subject to the charge is not finally appropriated as a security for the payment of the debt until the occurrence of some future event. In the meantime the chargor is left free to use the charged asset and to remove it from the security." Nature of the chargee's interest Several authors have suggested that the floating chargee, prior to crystallisation, may have no proprietary interest at all in the charged assets. However, this is inconsistent with cases (such as Spectrum) at the highest level which suggest a proprietary interest does exist. Alternatively, the floating chargee may have an inchoate type of proprietary interest, with characteristics that are proprietary but of a lesser order than the proprietary interest of a chargee with a fixed charge. Some authors have suggested that there is an interest in a fund of assets, but the nature and incidents of the interest remain unclear. This has received some judicial support, from Lord Walker in Spectrum, for example. Another possibility is that the holder of a floating charge may have the same quality of proprietary interest as a fixed chargee, but one that is subject to defeasance or overreaching by permitted dealings by the chargor with the charged assets. Flexibility Floating charges are popular as a security device for two principal reasons. From the secured creditor's perspective, the security will cover each and every asset of the chargor. From the charger's perspective, although all of their assets are encumbered, because