58.—An application for revocation of a patent may be made only on the grounds that—

( a ) the subject-matter of the patent is not patentable under this Act;

( b ) the specification of the patent does not disclose the invention in a manner sufficiently clear and complete for it to be carried out by a person skilled in the art;

( c ) the matter disclosed in the specification of the patent extends beyond that disclosed in the application as filed, or, if the patent was granted on an application which by virtue of section 24 or 81 is deemed to have been filed on the date of filing of an earlier application, it extends beyond that disclosed in the earlier application as filed;

( d ) the protection conferred by the patent has been extended by an amendment of the application or the specification of the patent;

( e ) the proprietor of the patent is not entitled thereto under section 16 (1).