With the sad deaths of both Bob Crow and Tony Benn in the same week much commentary in the bourgeois media ran along the lines of "we shall not seek their like again."

Even many of the more friendly commentators argued that the era of the labour movement represented by the RMT leader and Labour politician has gone for ever.

Such "end of history" arguments have been made ever since the birth of the labour movement - and yet it has survived.

Its precise forms may have changed over the years, but unequal societies and exploitation at work provide a continuing motor for workers' organisation and for political parties determined to challenge the status quo.

Moreover both Crow and Benn sought to actively change history.

Benn had to fight a parliamentary by-election for his Bristol seat in 1963 because he had earlier been disbarred following his elevation to the House of Lords on the death of his father Viscount Stansgate.

He wanted to be a democratically elected politician in the Commons not a hereditary peer in the Lords.

In order to do so he had to fight to get the law changed in order to give him the right to renounce his peerage.

It was also Benn, more than anyone, who introduced the idea of the referendum into British politics.

He floated the idea in 1971 when Labour was split over the EU. When the party won the February 1974 election it pledged to renegotiate Britain's terms of entry.

This done, Labour Premier Harold Wilson put it to a referendum in 1975 and won.

The idea was later adopted across the political spectrum as a way of giving the public a specific say on key questions of the day and it remains absolutely central to British politics 40 years on.

Finally, Benn changed the way in which leaders of political parties are elected when he pushed for a widened franchise beyond just MPs, to include unions and constituencies after Labour lost the 1979 election.

He was pipped to the deputy leadership by Denis Healey in 1981 but all parties now, including the Tories, include members in votes for the leader.

More astute commentators acknowledged that Benn had indeed changed British political history but noted that his left-wing ideas had failed to make an impact. Here again the record doesn't bear the point out.

The "Bennite" wave of the left declined in the Labour Party during the 1980s, and the 1990s saw the rise of new Labour.

Yet in the wider labour movement Benn, who had been in 1964 Wilson's spin doctor, saw his influence continue to grow.

His energy for meetings and protests around the country seemed boundless and, as president of the Stop the War Coalition, he was a key part of the largest demonstration ever held in British history against war with Iraq in 2003.

He famously withdrew from Parliament in 2001 to "devote more time to politics." It was an important point.

As some of his obituaries noted, he had the ability to have been a Labour prime minister. Yet he turned left and to the streets.

As his diaries - an almost unparalleled historical resource for the history of post-1945 Britain - make clear Benn had become increasingly disillusioned with the possibility of changing society in a significant way through Parliament.

Benn had a specificity as a political thinker and activist that can't be replicated.

However, as with Bob Crow, his ideas and approaches about how to change the world for the benefit of ordinary folk will certainly be.