P (newspapers) entered a printing agreement with T printers. NUJ was involved in a trade dispute with T, and therefore ordered its members working for P not to supply newspapers to T for printing. P sought an injunction to stop this practice and damages for tortious interference with performance of the contract. HL granted this, holding that the existence of a trade dispute between NUJ and T did not exempt it from tort liability in a dispute with P. It was irrelevant that T was owned by the same parent company as P.
Lord Diplock: He rejected the argument that because T and P were associated companies, NUJ really had a trade dispute with P too: They were separate corporate entities, and the Companies Act allowed the corporate veil to be used so as to let enterprises engage in new ventures with limited financial liability. This strongly militates against lifting the corporate veil except where parliament explicitly demands it (or on occasion if that intent of parliament is made clear from the statute). This is not the case here.