The horses pulling Bob Crow's hearse wore blue and white plumes on their heads; the colours of the RMT leader's beloved football team, Millwall.
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The threat level has been raised to critical by MI5's Counter-Terrorism Analysis Centre.
Sam Allardyce has quit as manager of Crystal Palace and retired from football management.
Authorities named Salman Abedi as the suspected attacker who detonated a bomb at the Manchester Arena.