Film-maker joins union leaders demanding transparency in 1972 builders' strike case that saw Ricky Tomlinson imprisonedFilm-maker Ken Loach joined union leaders and actor Ricky Tomlinson today to step up the pressure on the government to release documents relating to the case of 24 building workers arrested four decades ago after taking part in a strike.Loach said the case, which saw Tomlinson imprisoned in 1972, was one of the "great causes of our time"."It is an absolutely clear case so see let's see the strength of the trade union movement mobilised in the way it can be mobilised," he told a packed meeting in Westminster on Wednesday.Earlier this week it emerged that Chris Grayling, the justice secretary, had told surviving members of the "Shrewsbury 24" that documents relating to the case will be withheld for a further 10 years because of national security concerns.