Trade union activists at the traditional May Day march across the capital used this year's event to pay tribute to late RMT union leader Bob Crow and Labour MP Tony Benn.
TUC General Secretary Frances O'Grady said they would both be 'hugely missed'.
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The eagle-eyed resident spotted the mistake on signs just feet apart in south London.
The victim was attacked after bumping into a man at the ticket barrier at Putney Station.
The victim, who is his 40s, was found near the edge of palace grounds.