Union leader and firebrand Bob Crow has died suddenly at the age of 52.
Mr Crow, the General secretary of the Rail Maritime and Transport union, was in Brighton just days ago to speak at an event marking the 30th anniversary of the Miners' Strike.
In a statement on its website, the union said he died in the early hours of Tuesday morning.
"The union's offices will be closed for the rest of the day and the union will make further announcements in due course,"
At Saturday's 30th anniversary event at Friends’ Meeting House in Ship Street, Mr Crow said the union would continue to fight for justice for the families “wrecked” during the fight against pit closures, orchestrated by Margaret Thatcher’s government.
He said: “This year’s 30th anniversary of the miners’ strike is not only an opportunity to mark the extraordinary courage and determination of the mining communities in the teeth of the full force of a state-sponsored operations to break them, but also gives us a chance to ignite the same kind of fighting spirit and unity that we need to counter the attacks that the unions and the working class are under today.”
Speaking after the event an RMT spokesman said: “The event went very well, it was well attended and well received and it was a great way to commemorate the 30th anniversary of the strikes.
“One of the demands we put forward at the meeting was for a full investigation into the state operations against the miners which, in light of recent events, have been found to have been happening.”