Deputy leader's pledge on long-held principles

In a speech designed to reassure anxious activists, he pledged to keep up the pressure on key issues such as the Trident nuclear deterrent and scrapping tuition fees.

But he insisted that the coalition deal represents the "opportunity of a lifetime" for the Lib Dems to "deliver liberal democracy in Britain".

The address to the conference came after leader Nick Clegg 's Monday appeal for members to hold their nerve over compromises made for the power-sharing deal.

Mr Hughes said he was a "rock solid" supporter of the decision to form the coalition, praising the work of the Lib Dem Ministers, who had not become "any less radical or any less committed to freedom and fairness since they joined the Government".

But Mr Hughes also stressed that part of his job as deputy leader of the parliamentary party was to ensure the coalition's decisions "reflect the views and concerns of all my parliamentary colleagues and the wider party".

He said the party should use its influence in Government "sometimes to put on pressure, sometimes to warn and often to encourage".

The party would not back off its tradition positions, he said, but he also conceded activists "may not like everything that this Government will do".