The shopworkers' union Usdaw received boos at the TUC conference when it announced that it was opposed to the motion looking into a General Strike.
But Usdaw said the action would hand the Government "the biggest stick to beat us with".
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Nigel Farage warned on Friday Britain was "far less safe" and exposed to Cologne-style sex attacks because of open-door immigration.
Arthur Simpson-Kent, 48, admitted killing Ms Blake and their sons according to his lawyer.
Two brothers have been arrested on suspicion of murder after their parents were found dead in their own home over the weekend.