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.
More top news
One of London's smallest houses with just four rooms has gone on sale in Chelsea for over half a million pounds.
There are more tube strikes this week on the Central and Waterloo & City lines - here's what you need to know to avoid the worst of it.
Police are searching for a suspect after a man was seriously assaulted at the District Line tube station earlier this month.