He accepted privately, however, that the referendum may be delayed until after the election. "The idea that we must have it in this Parliament is not just good politics. A bit of flexibility is entirely right and proper," he told colleagues.
While putting the best possible gloss on the expected delays in implementing the report, Mr Ashdown was adamant he had got what he wanted - a momentum for change. He privately describes Mr Blair's style of leadership as "Zen Blairism", in which Mr Blair gives people space to come to a consensual agreement for change.
Mr Ashdown believes Mr Blair showed "feng shui" in his response to the death of Diana, Princess of Wales, and over trade union recognition. He is convinced that Mr Blair, in spite of the qualifications about timing, is quietly bringing the Labour movement towards electoral reform, even if it takes another eight years.
Downing Street sources said the Liberal Democrat leader was in close talks with Tony Blair over the past 48 hours about the presentation of the report. It was well received when Mr Ashdown gave an outline of the main findings - and Mr Blair's response - to the weekly meeting of the Liberal Democrat MPs on the eve of the report's publication.
Written by Lord Jenkins, the former leader of the Liberal Democrats in the Lords, it was always likely to be to Mr Ashdown's taste. Mr Blair's response was the test of whether Mr Ashdown's leadership would be at risk.
Mr Ashdown last night was insisting that the Prime Minister was keeping the options open on holding a referendum before the next election, although that was made less likely by the report suggesting that nothing could be changed until 2006 at the earliest.
Mr Ashdown said that many told him before the last election that electoral reform would only be put on the political agenda in a hung parliament, and that after Labour's landslide win, the Lib Dems would be sidelined.
But he felt vindicated in his high-risk policy of "constructive opposition" to the Blair Government, which has caused strains in his own party among critics who wanted to see clear gains from the closer relationship. Mr Ashdown feels that in spite of the difficulties over implementation, there is no doubt the direction the Prime Minister is going.