The rise in militancy in the early 70's was such that Labour -now in opposition- had to respond to the mood and turn left. Even Denis Healey would tell the 1973 Conference that his tax policies, once Labour was back in power, would "bring howls of anguish from the rich." And Wilson told the same gathering of plans for a National Enterprise Board (NEB) -extending public ownership- and for planning agreements between private industry and government.
The 1974 Manifesto itself talked of a "fundamental and irreversible shift in the balance of power and wealth in favour of working people and their families." Michael Foot would even enthuse that it was the "finest socialist programme I have seen in my lifetime."
But Wilson had in fact vetoed proposals to nationalise 20-25 major companies and excluded it from the Manifesto. He and a majority of the Cabinet neutered an Industry Bill and a White Paper radically cut the actual role of the NEB. It was to be a weak, ill-funded repository for lost causes and any planning agreements were to be voluntary (Marr 2007).
What's more, after the October 1974 General Election (when Labour was re-elected with a small majority) and the 1975 Common Market Referendum (when the right campaigned with the Liberals and Tories) Wilson sought to gradually marginalise and humiliate the Left. It culminated in the demotion -following City pressure- of Tony Benn from Industry Minister to Energy Minister in June 1975.
By this time Healey had embarked on a programme of public expenditure cuts and Tony Crosland -who had once said that spending would reform capitalism- was telling local authorities that "the party's over."