Andrew Grice: Since the scandal broke, Ed has barely put a foot wrong

Inside Westminster

As his aides downed Peroni beers left over from a party for Labour MPs, Ed Miliband was stone cold sober as he suddenly cut through the legal knots his advisers had tied themselves up in.

It was 10pm on Monday as Team Miliband struggled to finalise the wording of a Commons motion on News Corporation's bid for BSkyB. Ten drafts came and went, some trying to delay the Competition Commission's decision on the bid by linking it to the police investigation into hacking. Then Mr Miliband had a flash of inspiration, saying: "This House believes that is it in the public interest for Rupert Murdoch and News Corporation to withdraw their bid for BSkyB."

Simple and effective. The Conservatives might have opposed a motion about the Commission's inquiry, possibly aided by Lib Dem ministers. If the Commons spoke with one voice, even Mr Murdoch would find it hard to resist, Mr Miliband said. He was right. Before Wednesday's debate started, News Corp pulled its bid. "It's pretty rare to really change events in government; we have done it in opposition," Mr Miliband told aides.

It wasn't his only coup. He called for a public inquiry into hacking in April. Within minutes of the news breaking about Milly Dowler's phone being hacked, Mr Miliband pronounced it a "game-changer". Against the advice of some Labour voices, he decided to call for Rebekah Brooks to quit as chief executive of News International. When she finally departed yesterday, Mr Miliband could argue that she should have gone 10 days ago. He also tapped in another open goal by criticising Mr Murdoch's unrepentant interview in his Wall Street Journal. Mr Miliband said: "He still hasn't apologised to the innocent victims of hacking. He clearly still doesn't get it."

The Labour leader certainly "got it". On this issue, he was able to do the right thing and stay on the side of the public. One Cabinet minister admitted: "For the first time, Ed Miliband has cut through to the public. He has not put a foot wrong on this."

The transformation could not have come at a better time. The grumbling about his leadership from inside his party was growing again. Now his critics have fallen silent; he has bought time. The atmosphere at his two office parties – for MPs on Monday and Westminster journalists on Thursday – was upbeat, very different to what it would have been without his strong performance in a dramatic fortnight.

In contrast, the mood in Downing Street was bleak. Mr Cameron, who ran rings round Gordon Brown over MPs' expenses, has been running to catch up with Mr Miliband. "We have been behind the curve – frankly, all over the place," one No 10 insider confessed.

Mr Miliband's circle is not getting carried away though. His advisers are now focused on the $64,000 question: how to build on this, project himself on a wider front and tell voters something big about Labour's direction.

Five weeks ago, Mr Miliband made a speech about the need for "responsibility" both at the top and bottom of society. This was not posturing, this was the real Ed, a product of the deep thinking he has done about the challenges facing the country while he has been largely off the radar. It wasn't about the media, more about rich bankers and welfare claimants. But on Thursday his team concluded it was highly relevant to the hacking affair because "power without responsibility" has now been exercised by the press and the police, following the banks and MPs (over their expenses).

Nick Clegg made a similar point in an interview with this paper on Monday. He has prodded Mr Cameron on hacking and, unlike the two other parties, the Lib Dems have never cuddled up to press barons. They have long called for curbs on media ownership. But despite their strong credentials as an anti-establishment party, it will not be easy for the Lib Dems to clean it up while they share power with the Tories. Remember Vince Cable's brush with Mr Murdoch.

So perhaps the time has come for Mr Miliband's responsibility agenda. We will certainly behearing more about it. This road, while attractive, also has potholes. For a start, do the institutions Labour will "take on" include the trade unions? They threaten both an autumn of strikes and to block some of Mr Miliband's plans to dilute their influence in his party. There be may limits to his boldness.