First, the meaning of a "trade dispute" under TULRCA 1992 section 244 is confined to mean a dispute "between workers and their employer" and must mainly relate to employment terms. In "BBC v Hearn" Lord Denning MR granted an injunction against a strike by BBC staff to stop broadcast of the 1977 FA Cup Final to apartheid South Africa. He reasoned that this was a political dispute, not a "trade dispute", unless the union was requesting "putting a clause in the contract" to not do such work. Strikes against government legislation (rather than an employer), or privatisation, or outsourcing before it happens, have been held unlawful. However, at the least, any dispute over the terms or conditions on which workers do their jobs will allow protection. Second, TULRCA 1992 section 224 prevents collective action against someone who is "not the employer party to the dispute". "Secondary action" used to be lawful, from the Trade Union Act 1871 until 1927, and again from 1946 till 1980, but today it is not. This makes the definition of "employer" relevant, particularly where a trade dispute involves a company group. A worker's written statement of the contract may purport to say that the only "employer" is a subsidiary, although the parent company carries out the employer's function of ultimately setting the contractual terms and conditions. Further, any picketing or protest outside a workplace must be "peaceful" and there must be a picket supervisor. There are a limited number of outright prohibitions on strike action, but in accordance with ILO Convention 87 this is only for workplaces that involve the truly essential functions of the state (for armed forces, police, and prison officers), and only when impartial arbitration is used as an alternative.