Tributes poured in yesterday to the workers' towering champion Bob Crow after he died from a suspected heart attack aged 52.

Shock and grief gripped labour movement activists as news spread of the sudden death of the much-loved general secretary of the Rail, Maritime and Transport union (RMT).

The union closed its central London head office as a mark of respect but grieving trade unionists and members of the public laid flowers outside.

Meanwhile tributes and condolences flooded in from across Britain and around the world.

Labour MP John McDonnell, convener of the RMT group of MPs, said: "Bob was one of the finest trade unionists we have ever seen.

"He was simply loved by his members and re-elected time and again."

Grieving MP Jeremy Corbyn said: "Rest in peace Bob. You were a brilliant fighter, who gave your all for the working class."

Manuel Cortes, the leader of rail union TSSA who joined Mr Crow on the picket line during the recent London Tube strike, said: "It was a privilege to campaign and fight alongside him because he never gave an inch."

Fire Brigades Union general secretary Matt Wrack said: "Bob was a good friend to me personally and to the Fire Brigades Union as a whole.

"He was a strong leader for the labour movement and he'll be sorely missed by those who knew him."

His death is a "devastating loss" to Britain's trade union movement and to the cause of working people across the globe, declared GMB union general secretary Paul Kenny.

The Cuba Solidarity Campaign described him as "a wonderful friend to the working people of Cuba."

Mr Crow's older brother Richard described him as "one of those loveable little rogues, one of those guys that had bundles of friends."

He added: "People moaned that he lived in a council house, that he never drove a car - he lived a life of the average guy in the street and that's a rare thing these days.

"When people have a high office in life they fall for the big trappings of the flash cars and the big hotels and big houses. But Bob wasn't like that, he was a genuine person of the people."

Even his political enemies felt obliged to issue hypocritical public comments.

London Mayor Boris Johnson grudgingly admitted: "Bob fought tirelessly for his beliefs and for his members" while Prime Minister David Cameron's spokesman said his death was "very sad news."

And Labour leader Ed Miliband, who in 2011 refused to share a platform with Mr Crow at the Durham miners' gala, said he had "always respected his tireless commitment to fighting for the men and women in his union."

Mr Crow became RMT general secretary in 2002 following the death of former leader Jimmy Knapp.

Born in Shadwell, east London, Mr Crow started working on the London Underground at the age of 16.

All his life, he was an energetic fighter for the socialist cause. He was an implacable opponent of the EU, and in recent times he spearheaded the No2EU - Yes to Workers' Rights movement.

He would have been the lead No2EU candidate for London in May's EU elections.

Showing solidarity to the last, he spoke in Brighton just four days ago at an event to mark the 30th anniversary of the miners' strike.