Anne McElvoy explores how Labour MP Tony Benn turned from planning to populism amid the crises of the 1970s, and what this tells us about the competing strands of British socialism.

Anne traces how Labour Cabinet Minister Tony Benn turned from planning to populism.

Amid the crises of the 1970s, competing strands of British socialism struggled for dominance.

And one side, there were the statist technocrats who looked back to Labour's 1945 victory, and the building of the Welfare State.

But in the wake of the revolts of 1968, a new generation had revived a very different tradition - of a socialism focused more on radical self-realisation. Meanwhile, radical shop stewards forged a very different approach to trade unionism to the 'beer and sandwiches at Number 10' approach of the union General Secretaries.

So when Tony Benn moved from a mild, modernising emphasis on the possibilities of technology, and started marching alongside workers who had occupied their factories, and embraced identity politics too, it was a significant turn.

Anne explores what Benn's journey from Whitehall to the streets tells us about the paradoxes socialists faced in an era when they were often not on the margins, but in power.

With: Steve Fielding, Florence Sutcliffe-Braithwaite

Producer: Phil Tinline.