The document shows that the TUC held the first meeting of a "stakeholder task group" nearly a month before Mr Blair's "big idea" emerged in a speech to businessmen in Singapore on 8 January.
Union leaders first registered an interest in the concept at the end of October in a brainstorming session which decided to establish the task group.
On 13 December, at the first meeting of the working party, John Monks, TUC general secretary, offered the opinion that the Labour Party was "cautious" on the issue and that such reticence gave unions the opportunity to lead the way.
The Tories will seize on the revelations as the most concrete evidence yet that Mr Blair is following an agenda set by unions. Ministers have already denounced the slogan as a strong indication that Labour wants a return to the corporatism of the 1970s. Conservatives point to an article by Mr Monks in The Times in which he registered unions' determination to be a "stakeholder" on behalf of working people.
The minutes of the first task group meeting report Mr Monks as saying "stakeholding was a political and sensitive issue, which had raised considerable opposition, and on which the Labour Party was cautious. There was therefore an opportunity for trade unions to lead." In a remark which shows how far unions have come since the days when socialism was the political goal, Mr Monks then led a discussion on "what kind of capitalism we wanted".
Roger Lyons, chair of the group, said unions wanted to influence the discussions on "corporate governance" conducted by Shadow Cabinet members who are to present a paper to the party's next policy forum on the subject. "People at work want their interests reflected and it is not something which is necessarily taken on board by the Labour Party."
It was the responsibility of TUC unions to work out how employees would be involved in a stakeholder society, said Mr Lyons, who is general secretary of the union Manufacturing Science Finance, one of the party's biggest affiliates.
Mr Lyons said union leaders first heard the idea in a book by Will Hutton called The State We're in. "His analysis of the problem was very influential, but his prescriptions left a lot to be desired."
The task group has arranged a series of seminars on the subject culminating in a special conference of all unions during which the TUC's interpretation of the slogan will emerge.
The annual congress in September will also spell out what is required from such a society, Mr Lyons said.
The document sets out the aims of the TUC group which will be to "highlight the role of trade unions" and promote the concept to employers, investors, political parties and the media. It will also seek to "develop an analysis of the economic and social case for moving to a stakeholder society".