William Hague yesterday launched the Tories' Welsh manifesto but immediately ran into trouble over his party's tax plans and their grasp of Welsh.

Hague's difficulties began with a report in yesterday's Financial Times in which Oliver Letwin, shadow treasury chief secretary, said his party could cut tax by £20 billion by 2004. The official party line, stated in the manifesto, is for tax cuts of £8 billion.

Yesterday, Hague had to repeatedly confirm to reporters at the manifesto launch in Cardiff that the £8 billion figure was the correct one, saying "£8 billion is the figure we have given. It remains the figure."

Labour was quick to seize on the apparent gaffe, Tony Blair and Gordon Brown mocking what they called "Hagueonomics", where the Tories would "tax less and spend more with the same amount of money."

Hague also had problems with the Welsh language, despite being married to a Welsh speaker. The final version of the manifesto could not be published because of spelling errors and when invited by journalists to say his party's slogan "It's time for common sense" in Welsh, he declined.