If you listened very closely on Thursday evening, around about the time David Cameron was on his feet delivering a speech to parliamentary correspondents at Westminster ("The last time I was at a dinner this posh Boris spent the rest of the night in prison"), you could just about hear the sound of chairs being kicked around Labour party HQ.

For days Team Miliband had been trailing the Labour leader's upcoming economic speech, promising that, in the manner of a vengeful action hero, he would call down "a reckoning" on the heads of those renegade bankers, part of an election-winning crusade that would heal, once and for all, "Britain's broken banking system".

And then George Osborne just happened to mention in a BBC interview that – this wasn't his decision of course – but the Low Pay Commission could probably now consider restoring the minimum wage to its "real value". How much was that? Well, if Nick Robinson twisted his arm for a figure, how about an 11% bump next year to £7 an hour?

If your core message is the cost of living crisis, and you're about to make a major speech on the economy the next day, this is what is known as an unhelpful intervention.

A "strengthened" minimum wage did get a mention in Miliband's speech on Friday – a blink-and-you-missed-it flicker in a long list of Labour's aspirations for the next parliament – but there was otherwise not so much as a nod to Osborne's attempted leg-chopping tackle.

His theme, instead, was the "new economy", a phrase repeated six times in his speech, though not – it was a political address, after all – defined in any intelligible sense. Cameron and Osborne's plan was "not a recipe for building a new economy", it was "a recipe for clinging on to the old economy". Only in tackling the banking system could Labour prove it was serious about constructing said novel economy. The stakes, friends, were "incredibly high. To build the new economy, to leave behind the old economy in the past". Got that? Good.

Ed Miliband may not – unlike some at the Treasury, as it emerged this week – have had taxpayer-funded acting lessons at Rada, but he has certainly mastered the key prime ministerial requirement of delivering a lengthy speech without notes. And yet he's much more human and convincing when speaking for himself than when repeating from memory, and occasionally garbling, the metaphors of his speechwriters.

"The cost of living crisis is about the pound in people's pocket. But it's much, much deeper." Deeper than people's pockets? Well I suppose they aren't deep pockets, which is why there's a cost of living crisis in the first place. "And because the problems are deep, the solutions need to be deep as well. Friends, that is the task of the next Labour government." That's deep – I think.

By contrast, the Miliband who took questions from the floor was relaxed and funny. His problem was that his awkwardly off-message supporters kept asking about things other than the economy. "First of all, can I thank you for your stance on Syria," said one elderly questioner. Secondly, could he promise that a future Labour government wouldn't engage with "backward states like Qatar and Dubai"? There was then something about fracking and the selling of Heathrow airport to France. "What are you going to do about that?"

"Well, I'm really pleased I called on you," said Miliband. His next questioner was from the Financial Times, who obligingly asked about bankers' bonuses.

"I will say one nice thing about the banks," said Miliband, suggesting that some at the top now did recognise the need for major change. That really would be a new economy.