Mick Cash, the RMT's senior assistant general secretary, said Mr Crow's death had rocked the trade union movement, both in this country and around the world.
The thousands of messages of condolence from every part of the globe are a testament to the courage, leadership and strength that Bob shared with so many people.
Whilst Bob Crow's funeral itself will be a strictly private affair, his friends and family recognise that many people will want to show their solidarity, respect and support, both on the day itself and on May Day.
These arrangements give everyone a chance to play their part.
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Transport Secretary Chris Grayling believes Network Rail should share the responsibility with private train operating companies.
Two vehicles were swallowed up by the sinkhole on Sunday night, killing Dora Linda Nishihara and injuring one man.
Elliott Livingstone, aged three, spent most of his life in hospital before the operation in April.