 Complete the following phrase:  On 30 November, 1983, over four thousand trade unionists attended a mass picket. The police brought in riot-trained Police Support Units from five surrounding areas and the confrontation became physical. The NGA speaker van was attacked and overturned by police, while squads with full riot gear repeatedly charged the pickets. The National Graphical Association immediately suspended mass picketing. For the first time in post-war Britain, para-military policing more akin to that used in 