Nick Clegg: 'I am as much of a radical as ever' Press Association

Nick Clegg brushed aside a conference voting reverse on the health bill to claim the 2015 election will not be a destination, but a staging post to a new liberal, one-nation Britain.

In a speech closing the Liberal Democrat spring conference, he insisted his party had only just got started creating a liberal country.

The deputy prime minister hinted at the tax changes he is still seeking in this month's budget, saying he wanted to call time on the tycoon tax dodgers, and promised what he described as "big increase" in income tax thresholds.

He rounded on Lord Oakeshott – a close ally of Vince Cable, the business secretary – who has attacked Clegg's proposals, saying: "The only person in the party who is against a tycoon tax is one of the party's tycoons."

Despite suggestions that some in his party are unimpressed by the idea of a minimum tax income, he said: "We will call time on the tycoon tax dodgers and make sure everyone pays a fair level of tax. Too often, rather than paying their dues, the wealthy pay their accountants to get them out of it. Avoiding tax, minimising the amount they have to contribute – that's the name of their game. Boasting about the latest wheeze for moving an asset here, a property there and a loophole everywhere. All to make the tax bill lower.

"Few things make me angrier as the unemployed struggle to find work, as ordinary families struggle to make ends meet, as young people struggle to get on the housing ladder: the sight of the wealthiest scheming to keep their tax bill down to the bare minimum is frankly disgraceful. Multimillionaires avoiding tax by moving their money around."

He also hinted he was opposed to seeing the top 50p tax rate abolished in this budget. He said: "The last big tax-cutting budget was in 1988. Nigel Lawson cut billions from the tax bills of the highest-paid workers – a budget for the few, not for the many. But this year's coalition budget must be a budget for fairness – not an 80s Lawson budget but a modern liberal budget."

He touched only briefly on the controversy over the health bill, and the vote to delete an amendment calling for the bill to be supported at its third reading in the Lords.

Clegg insisted it was not a Liberal Democrat bill, but that it was a better bill for the intervention of Shirley Williams the Lib Dem peer.

"The value of coalition has been proven because this is a coalition government. The health bill was stopped in its tracks and rewritten because this is a coalition government. Competition will be the servant of health care, not the master because this is a coalition government," he said.

"This is a bill for patients not profits. It is not a Liberal Democrat health bill but it is a better bill because of the Liberal Democrats, a better bill because of you."

But he promised: "Before 2015, because of us there will be: the first gay marriage and an end to child detention; the first bank levy; an end to huge tax loopholes for the rich; the first elections to House of Lords; an end to control orders; the first coalition government in our lifetimes and an end to the myth that Liberal Democrats can't govern."

He said: "Our biggest challenge is to rescue our economy. We need to sort out the financial mess Labour left us. But we need economic reform too. We need a new economy that serves not one square mile, but one nation. Not creative accounting, but creative industries. Not the City, but all our cities. Healing the divide between north and south."

Without mentioning elected city mayors, a policy his party does not support, he promised to "free" cities by striking deals that give them freedom to raise more cash.

He also sidestepped Tory demands for further workplace deregulation, saying he wanted to "rebalance power in the workplace. "That's why I want us to build a 'John Lewis' economy," he said, "where workers have a real stake. Not capital versus labour, bosses versus workers but modern enterprises built on shared endeavour and shared profit."

Clegg also directed his fire at the chancellor, George Osborne, for suggesting in his conference speech that there was a choice to be made between being green and backing growth. Clegg said: "What a load of rubbish. Going for growth means going green. The race is on to lead the world in clean energy. The new economic powerhouses – China, India, Brazil – are competing.

"So the choice for the UK is simple: wake up, or end up playing catch-up. Going green is not a luxury for the good times. It is the best road out of the bad times.

"Our party is the green party of government. We have always been a green party. And let me tell you this: we always will be a green party because we need an economy fit for the future to pull us out of this economic downturn."

He defended his plans for a youth contracta nd said he would make no apology for the idea of encouraging work experience.

"Labour's benefit rules," he said, "actually penalised unemployed youngsters for getting work experience. So thousands of them ended up on the sofa, glued to the TV, cut off from the world of work, wasting time and losing hope.

"Our policy means young people can get up and get on, keep their skills alive, keep up the habits of a working life and improve their chance of landing a job. There is nothing liberal about leaving our young people to waste away on the dole."

He added: "We have shown that two parties, two very different parties, can govern together. Never again will the political Luddites be able to say that coalitions don't work. Coalition is working, it is has been tested and it has passed the test.

"The other parties are bound and gagged by vested interests. We are not. The other parties are hemmed into certain parts of the country. Look at the electoral map: blue seats in the south, red ones in the north. Look at where the money comes from: trade unions on one side, City financiers on the other. That is why we can say today: the Liberal Democrats are the only true one-nation party."