Mayor of London Boris Johnson said he was shocked and saddened to hear about the death of union leader Bob Crow.
Paying tribute to the improvements in London Underground made by his political opponent, he said his death leaves a massive gap behind and praised his indefatigable defence of his members views and interests.
The late Bob Crow took the trade unions back to their roots and left his members better off - and attracted many critics along the way.
The trade union movement is in shock after the sudden death of rail union leader Bob Crow, who passed away early this morning aged 52
The RMT leader was demonised by Fleet Street, often loathed by commuters, but adored by his members.