Union leaders have paid tribute to Bob Crow following his death at the age of 52.
The general secretary of the Rail Maritime and Transport union (RMT) died from a heart attack, according to reports.
It has been confirmed Mr Crow, who lived in Woodford Green, died at Whipps Cross Hospital, Leytonstone, at around 7am today.
UNISON General Secretary, Dave Prentis, said: “I am shocked and saddened to hear of the death of Bob Crow. UNISON members will want to send their sympathy to his family and friends.
“Bob was a tough, no-nonsense union leader who always did his best for his members. And it was very much down to his tough stance that their pay and conditions improved.
“Despite all the flack he got, he stood his ground and was a great member of our trade union family. His loss will be felt across the whole trade union movement”.
Trade Union Centre (TUC) General Secretary, Frances O’Grady, said: “This is shocking news. Bob was an outstanding trade unionist, who tirelessly fought for his members, his industry and the wider trade union movement.
“He was always a good friend and comrade to me. We will miss him, and our thoughts are with his family and the RMT at this difficult time.”
The RMT offices will be closed for the rest of the day and further announcements are expected.