"Hallelujah", was one response. "Fantastic," another. "It makes perfect sense," added a third.

At a time when many within the green business movement had all but given up lobbying for a more cohesive joined up approach to tackling climate change, the prime minister blind-sided everyone by announcing the formation of a new Department for Climate Change and Energy.

The move will inevitably be overshadowed by the Lazarus-like cabinet return of Peter Mandelson - he of the two previous cabinet resignations, undisclosed home loan, and "prince of darkness" epithets.

But in the long term it is the creation of the new climate change and energy ministerial brief that could prove the most significant and enduring legacy of Brown's first major reshuffle.

It is easy to see why many green business groups will be so delighted at the decision.

For years anyone attempting to deal with Whitehall on green matters has had to navigate the at times brutal turf war between the department for business, enterprise and regulatory reform (BERR) and Defra.

Primarily through their differing approaches to energy policy, but also as a result of the ideological differences that exist between one department set up to cut regulation and another tasked with protecting the environment, the two departments with the greatest responsibility for tackling climate change have repeatedly been described as being at "loggerheads" - that is when of course they are not trying to throttle each other.

Bringing these two factions together can only help dilute the tensions and ensure that carbon considerations play an even greater role in energy decisions than they do currently.

Moreover, the appointment of Ed Miliband suggests that the new department will have real teeth. He is hugely respected by Gordon Brown and has been a close ally of the prime minister for many years, yet has somehow managed to avoid the "arch-Brownite" tag and appears to be reasonable well regarded across Labour's increasingly divided political landscape.

Critically, he should have the authority to make things happen. As is the case with businesses looking to drive forward an environmental strategy, developing a dedicated climate change or CSR department is only an effective strategy if that department is given the power to impose its policies on all departments that have to adhere to the central goal of cutting emissions.

In this light the appointment of a minister known to have the prime minister's ear is crucial. It might be the politics of the playground, but the fact that Miliband will be in a position to tell Brown which departments aren't playing ball can only help establish the new office as a centre of power.

In addition, the department already has a robust feel to it. The Conservatives this week sought to reinvigorate their environmental agenda and as such it is unlikely that any in-coming Tory government would seek to get rid of it in another reshuffle. But even if they wanted to the fact that climate change is sitting right there in the departments name makes it almost impossible for any government to kill it off without in some way admitting that they don't see climate change as a problem. This new department is with us for the long haul and its influence can only grow.

And yet those hailing the new department as a momentous turning point in the government's fight against climate change are perhaps guilty of overstating the matter.

The fact is that just because energy and climate change are rubbing shoulders in the same department does not mean they are suddenly going to become bosom buddies.

One of the first issues in Miliband's in-box will be Kingsnorth and the issue will be no less vexed just because a new department is addressing it. Block the plans for a new plant and the business lobby will be furious, grant approval and the department supposedly responsible for tackling climate change will have its credibility shot to pieces before the new business cards have even been printed.

Find a way to through the Kingsnorth imbroglio and the in-box is will still sagging under the weight of issues that need addressing.

It is worth noting that for all the government's claims that it is leading the fight against climate change, this week the IEA rated the UK's renewable energy strategy 31st out of 35 developed countries.

On balance, a new climate change and energy department should help address this appalling scenario, but as Ed Miliband tonight toasts his promotion let us all hope that he is under no illusions as to the scale of the challenge he now faces.

Right, I'm off to book me a spot on a climate change tackling space ship.

Have a good weekend,

James