s 543 Numbering of shares
(1) Each share in a company having a share capital must be distinguished by its appropriate number, except in the following circumstances. (2) If at any time— (a) all the issued shares in a company are fully paid up and rank pari passu for all purposes, or (b) all the issued shares of a particular class in a company are fully paid up and rank pari passu for all purposes, none of those shares need thereafter have a distinguishing number so long as it remains fully paid up and ranks pari passu for all purposes with all shares of the same class for the time being issued and fully paid up.