As Labour leader Ed Miliband ended what was a dreadful summer for his leadership, one question hung over him: Can he do any better than this?

His answer came in a leadership-defining conference speech in which he turned that question around and fired it at Prime Minister David Cameron and his government declaring, time and again: "Britain can do better than this".

He promised a Labour government under him would be on the side of ordinary, working people and would stand up for the weak.

He said he would freeze energy prices for almost two years if elected, while abolishing the regulator Ofgem and replacing it with a more powerful watchdog.

It was a pledge that immediately brought claims that he was returning to a socialist-style policy of price-fixing and risked reviving the "Red Ed" tag. But the delegates loved it.

Leadership abilities

He repeated his promise to abolish the bedroom tax, increase the minimum wage, cut rates for small businesses and build thousands more homes.

And he won a standing ovation when he said that Labour would have to "rescue the NHS from the Tories all over again".

For the 60-plus minutes that he addressed his party faithful, without notes or autocue, they bought every word of it.

Probably the key line was when he addressed the central issue that has dogged him ever since he beat his brother David to become Labour leader in 2010 - his leadership abilities.

In a direct challenge to the prime minister, he declared: "If you want to have a debate about leadership and character, be my guest."

The real test, he said, was whose side you took when the chips were down.

"If you want to know the difference between me and David Cameron, here's an easy way to remember it. When it was Murdoch versus the McCanns, he took the side of Murdoch.

"When it was the doctors versus the tobacco lobby, he took the side of the tobacco lobby. When it was the millionaires wanting a tax cut...

"Frankly, here's an easy way to remember it. David Cameron was the prime minister who introduced the bedroom tax. I'll be the prime minister who repeals the bedroom tax."

And in a sentence that sounded like an election slogan which will be heard over and over again over the next 20 months, he said: "David Cameron is strong at standing up to the weak but weak when it comes to standing up against the strong."

Slipping away

No one in the hall doubted that this was the most important speech Miliband had to make, both to underpin his leadership, which has come under fire from some even in his own ranks, but also to set the party's sights on the election battle to come.

The great fear was, and may still remain, that Miliband has a history of making memorable and powerful conference speeches which gain him only a temporary advantage.

In 2011 he famously talked about capitalist "predators versus producers" and a year later he introduced the One Nation Labour label. Those ideas went down well with the party faithful and won some wider praise but they did not gain traction and he found his advances quickly slipping away.

Within minutes of him leaving the conference stage, opponents had started tweeting "Britain can do better than Miliband" and claiming he was signalling the most left-wing manifesto since Labour's infamous 1983 "longest suicide note in history".

His energy policy drew particular opposition with utilities companies suggesting it would halt investment.

But with voters unlikely to have much sympathy with energy supply firm bosses who have increased their bills substantially in recent years, this is a fight Miliband is clearly happy to engage.

The immediate reaction from delegates and the all-important union leaders was good. But that old question remains to be answered.

Miliband may have delivered his best performance yet but was the content of the speech enough to persuade voters thathe has the character and leadership credentials to occupy 10 Downing Street in 2015?