 Complete the following phrase:  During a decade of industrial unrest, the Grunwick dispute became a cause célèbre of trade unionism and labour relations law, and at its height involved thousands of trade unionists and police in confrontations, ... with over 500 arrests on the picket line and frequent police violence. The total of 550 arrests made during the strike was at the time the highest such figure in any industrial dispute since the General Strike of 1926. Journalist Paul Foot described the dispute as a central battleground between the classes and between the parties. The dispute was reported nightly on the national television news, depicting the often violent clashes between the supporters of the strikers and the Metropolitan Polices Special Patrol Group. Grunwick was the first time that this paramilitary police unit had been deployed in an industrial dispute. The mostly female, immigrant, 