Labour leader Ed Miliband
Ed Miliband sparked debate with energy price freeze pledgeReuters

Ed Miliband's high-risk decision to take on the big energy companies has paid dividends for the second day after the regulator, Ofgem, announced there was to be a full-scale competition inquiry into the industry.

Just 24 hours after one of the so-called Big Six firms, SSE, announced a price freeze until at least 2016, Ofgem reported there was evidence of a lack of real competition in the industry combined with a "tacit co-ordination" on the size and timing of price increases.

The words "cartel" and "price-fixing" were not used but the implication was there for anyone who wanted to find it.

Once again, the coalition government attempted to take credit for the decisions, arguing it was their policies that had created the conditions for both the price freeze and the inquiry, things they had previously opposed.

But, in a Commons statement, energy secretary Ed Davey gave the game away when he declared the government had been determined to act to protect consumers, adding that was why in October last year it had announced annual reviews of the industry.

And that is the point. It was last September that Ed Miliband launched his attack on the energy firms and promised a Labour government would freeze prices for 20 months.

It was in response to Labour's initiative that the coalition was moved to act, fearing Miliband had hit on an issue that struck a real chord with voters.

The pressure is now on the other Big Six firms to "tacitly co-ordinate" with SSE and freeze their prices as well.

Shadow energy secretary Caroline Flint also suggested the regulator itself needed to be investigated for having consistently failed to get a grip on the problem.

She added: "The only reason we are having this today is because of the speech from Ed Miliband at the Labour conference last year."

That is a powerful point and one that Labour will continue to make in the hope that the agenda has moved back onto their turf after a difficult few days in the wake of George Osborne's highly-political budget and the improving economy.

And, if there is now a series of other announcements from the Big Six, it is possible things will move back in Miliband's favour, at least for the time being.

There may also be a backlash after Centrica boss Sam Laidlaw told the BBC the competition inquiry might hit investment in the industry and could even create "an increasing risk" of power outages.

That is exactly the sort of language Labour has previously highlighted to suggest the companies were too powerful, unaccountable and needed to be broken up.

They also play directly into Miliband's narrative that he is the only one ready to stand up to powerful interests while the government speaks for them.

The Labour leader has faced a backlash of his own, with many commentators and Tories suggesting he has failed to see a significant difference between a government-imposed price freeze and a voluntary one adopted by the companies.

That, however, ignores the fact that it was clearly Miliband's, and later the coalitions' political intervention that prompted SSE to freeze bills in the first place.

And Miliband will hope, consumers will not worry too much about the alleged difference, so long as they are benefitting from reduced costs. He will also want to ensure that he gets the credit for that.