(56) Works in which—
(a)any hydrocarbons are used for the production of ethylene or propylene or other olefines; or
(b)(i)ethylene or propylene or other olefines or mixtures thereof are used in any chemical manufacturing process, not being a chemical manufacturing process defined elsewhere in this Schedule; or
(ii)any product of the processes to which sub-paragraph (b)(i) applies is used, except as a solvent, in any subsequent chemical manufacturing process, not being a chemical manufacturing process defined elsewhere in this Schedule; or
(c)ethylene or propylene or other olefines or products of processes defined at sub-paragraphs (b)(i) and (ii) or mixtures thereof are polymerised.