The relevant sections from the Trade Union and Labour Relations (Consolidation) Act 1992 have been quoted on this, and the other thread many times. It is not rocket science, and most of us are able to understand the rules in a few minutes. However, a major union, such as Unite, with all of their legal advice, is unable to follow the basic law.
Holding off an injunction until the day before yet another stoppage is part of a carefully thought out plan
Post #168 (page 9)