Union Congress leadership failed to provide any support, as they were too closely bound to management and government circles, with the result that strike leaders were blacklisted. Anti-union legislation was introduced by central government. These events were recreated in Ken Loach's film The Rank and File, although the BBC insisted on a change in the name and location of the company, so that the film is set at a Wilkinsons in the West Midlands. In late 1985, Pilkington was the subject of an unfriendly take-over bid from BTR Industries, a large British-based conglomerate group. Pilkington's efforts to reject the bid were assisted by its employees, the town and some government ministers. Their joint successful work was followed by a withdrawal of BTR's offer in early 1986. Litigation Pilkington aggressively protected its patents and trade secrets through a network of licensing agreements with glass manufacturers around the world. The modern "float" technique (pouring the molten glass on a layer of very pure molten tin) became commercially widespread when Alastair Pilkington developed a practical version, patented in the late 1950s and early 1960s. As Pilkington plc owned all but one of the manufacturing plants around the world employing the float process Pilkington had a monopoly. Although the patents had expired by the early 1980s, Pilkington had licensed their use, and required the licensees to keep the details of the float glass process secret. Guardian Industries had tried to challenge Pilkington's dominance but had made a secret agreement to prevent new entrants into the market, with Guardian taking the lead to enable Pilkington, a British company, to reduce its exposure to United States antitrust law. In May 1994, the United States Department of Justice filed suit on the grounds that Pilkington had created a cartel by exercising control over the markets in which its licensees could sell float glass and construct float-glass manufacturing plants, and over the customers within each market to which each licensee could serve. It was claimed this was a violation of the Sherman Antitrust Act, because Pilkington's patents had expired and any trade secrets which it might have had in the process used by the licensees had long since become publicly known. On the same day, the government and Pilkington filed a proposed consent decree, which enjoined Pilkington from enforcing these restrictions against its US licensees, or against US non-licensees, or against non-US licensees wishing to export either technology