Media playback is unsupported on your device Media caption Tim Farron's pledge to Charles Kennedy: 'We are so proud of you, and we will rebuild and we will fight back and we will do it in your honour'

Tim Farron's "mission" as Liberal Democrat leader is to get them "back in power at every level throughout Britain", he has told activists.

In his first big conference speech, Mr Farron said the Lib Dems were now the only "credible" opposition to the Conservatives.

And he invited liberals from across the political spectrum to join the party.

He also mounted his strongest attack yet on David Cameron's "pitiful" response to the refugee crisis.

Follow reaction to Tim Farron's speech on Politics Live

Mr Farron, who was elected leader in July following the party's general election rout, which saw them lose all but eight of their MPs, warned activists against retreating into the comfort zone of opposition.

Refugee crisis

He refused to distance the party from its coalition with the Conservatives, telling activists: "I am proud of what we did in government."

But he mounted an angry attack on David Cameron's handling of the refugee crisis and called on the government to opt in to the EU plan to" take our share of the refugees", although he did not specify a number.

In an impassioned account of a visit he had made to a refugee camp in Calais, which earned a standing ovation from activists, he accused Mr Cameron of making "the minimum effort for the maximum headlines".

"It's pitiful and embarrassing and makes me so angry because I am proud to be British and I am proud of Britain's values.

"So when Mr Cameron turns his back on the needy and turns his back on our neighbours I want the world to know, he does not speak for me, he does not speak for us, he does not speak for Britain."

Media playback is unsupported on your device Media caption Tim Farron speaks about the Lib Dem record in office and invokes Joni Mitchell as he tells them 'You don't know what you've got til its gone'

Mr Farron has seized on Jeremy Corbyn's election as leader of the Labour Party as an opportunity to reclaim the centre ground of British politics.

"If others wish to abandon serious politics, serious economics, that's their lookout," he told activists. "But you can be certain that the Liberal Democrats will occupy every inch of that progressive liberal space because you cannot change people's lives from the glory of self-indulgent opposition.

"Instead, I want us to be serious about power."

He accused Mr Corbyn of being "ambivalent" about Britain's membership of the EU, vowing to fight for the UK to remain in the bloc in the forthcoming referendum.

The Lib Dems had lost in May because voters did not know what they stood for, he told activists in Bournemouth, and it was now time to set out a "strong and clear liberal vision" for the UK. He said the party's fightback would begin at next year's Scottish and Welsh elections and in town hall elections across the UK.

Small business

The Lib Dem leader said the party remained committed to abolishing the structural deficit by 2017-18 - but not on the back of the poorest and lowest paid, saying: "We must all play our part, based on our ability to pay."

He pledged that the Lib Dems will be on the side of small business, "tearing down the barriers that stop businesses from fulfilling their ambitions".

Analysis by BBC political editor Laura Kuenssberg

Image copyright PA

Tim Farron didn't need to introduce himself to the audience in the Liberal Democrat conference hall. For years he has been a popular campaigner in the party, and during the years of coalition he wasn't shy of having a swipe at his colleagues who had gone into government.

But it was his first big set piece speech as the party's leader and after the Lib Dems' appalling loss at the general election, his task was not really to punch through to the general public. Let's be realistic, with the party so diminished, most voters won't be paying that much attention.

Instead it was to persuade his party that all is not lost.

On that, a passionate and well-delivered speech, peppered with anecdotes from his own childhood, hit the right notes. He tried, and in the most part succeeded, to combine his brand of Northern charm, with the heft of a serious politician.

Read more from Laura

He also used the speech to set out plans to solve the housing crisis in England by building 300,000 new homes a year.

He said he was inspired to get into politics as a teenager by watching a repeat of the 1966 film Cathy Come Home, a ground-breaking drama documentary on homelessness that led to the foundation of the charity Shelter.

Image copyright Reuters Image caption Tim Farron arrives for his speech with party activists

Image copyright Reuters Image caption Lord Ashdown has not always been a Farron fan, but saluted his speech

Image copyright Getty Images Image caption Nick Clegg and Sir Menzies Campbell seemed to enjoy the speech

"Housing is the biggest single issue that politicians don't talk about," said Mr Farron.

"Well, we are going to talk about it, campaign on it, go on and on and on about it, and make a difference to the millions who have been ignored.

"Communities up and down this country have spent 25 years building housing association homes, picking up the pieces of Mrs Thatcher's destruction of council housing, and we will not allow David Cameron to destroy that work too."

Mr Farron says he will instruct Lib Dem peers in the House of Lords to block David Cameron's plan to give housing association tenants the right to buy their homes in an attempt to block them.

Other Lib Dem policies aimed at solving the housing shortage include:

Lifting the borrowing cap on local authorities, which the party claims could result in an extra 80,000 homes over five years

A ban on advertising UK properties to overseas investors first

A government-backed housing investment bank to provide capital for new homes

10 new garden cities in England, including five major new settlements along a garden cities railway between Oxford and Cambridge

He ended his speech with an appeal to "liberally-minded" people from across the political spectrum to join the party, as 20,000 people have already done since May.

"There are millions of people in Britain who know in their hearts that they are liberals. We need to convince them now to become Liberal Democrats."