Landale online: What a difference a year makes
If you want to grasp just how far this government has come in the last 12 months, take a glance at the preface to the Coalition Agreement.
This was the 34-page policy document hammered out by a small group of Conservative and Liberal Democrat MPs exactly a year ago, the prism through which the coalition has governed ever since, the holy writ by which all of Whitehall runs.
It is signed personally by David Cameron and Nick Clegg.
The preface stated: "In the crucial area of public service reform, we have found that Liberal Democrat and Conservative ideas are stronger combined.
"For example, in the NHS, take Conservative thinking on markets, choice and competition and add it to the Liberal Democrat belief in advancing democracy at a much more local level, and you have a united vision for the NHS that is truly radical: GPs with authority over commissioning; patients with much more control; elections for your local health board.
"Together, our ideas will bring an emphatic end to the bureaucracy, top-down control and centralisation that has so diminished our NHS."
Division and recrimination
So there you have it. One year ago Messrs Cameron and Clegg were hailing health reform as a beacon of ideological common ground between their parties, a model of how the coalition was more than the sum of its parts.
Today health reform is the focus of bitter division and controversy and recrimination between the Conservatives and Liberal Democrats.
Mr Clegg is using the issue to demonstrate a new distance from the Conservatives in the wake of his election drubbing, while Mr Cameron is promising "significant changes" to water it all down and assuage angry doctors and nurses.
Thus the reality of coalition on its first birthday: policy rows at the fraying edges of the Coalition Agreement, and personality tensions after a bruising referendum on the alternative vote that saw coalition ministers accuse each other of being Joseph Goebbels and Jeremy Paxman.
Where once ministers dreamed of some kind of ideological coming together, where liberalism blended with the Big Society, there is now a cold, businesslike transactionalism that has seen fraternity replaced by formality.
And yet, one year on, it would be wrong to view the coalition simply through the viewfinder of the present.
This is a coalition that came from nowhere. Most people were expecting a minority government.
In 1997, Labour stuttered and hesitated over what to do with its unexpected landslide. This coalition has roared into action with at times dangerous hyperactivity.
Just run your mind through a few of the things it has been doing.
It has begun radical reforms - and for once the adjective is more than an alliterative cliche - to the welfare state, the schooling system, the funding of universities, the state pension.
These are the long-term, heavy lifting, tricky public policy issues that past governments have been unwilling or unable to tackle.
All of that, of course, on top of the deepest, fastest spending cuts in recent history, begun at astonishing speed in a flurry of budgets and reviews.
And let us not forget that the coalition has entered a new armed conflict in Libya, with David Cameron - like so many of his predecessors - coaxing a reluctant Washington into committing US forces into military action.
None of this is to say that any of these policies will be successful or will not come unstuck or - in the case of war - drag on.
But the sheer scale of the ambition and speed is breathtaking. The rush to avoid Labour's hesitation and tackle the tough stuff early on has obviously come at some cost.
The errors on school buildings, forests, tuition fees and health all bear the hallmarks of rushed policy.
But just imagine how it may have been without a coalition with a solid parliamentary majority.
A minority Conservative administration would have been hamstrung by its lack of authority and numbers, forever subject to the whims of its backbenchers as the party was through much of the 1990s.
How powerful the likes of Bill Cash and other Conservative MPs would have been!
The next year will be harder. There will be less good will. The spending cuts will begin to be felt in earnest.
Liberal Democrat supporters abandoned their party this year in disgust at their presence in a coalition with the Tories.
Next year Conservative supporters will begin to lose their child benefit and their libraries as their taxes and tuition fees go up. 2012 may be the year that Tory voters register their protest in the elections to come.
But at the moment, for all personal spats and the policy rows, the logic all still points to the coalition enduring.
The parliamentary arithmetic means both sides need each other. Neither side desires a general election.
There is no reason to leave the coalition, at least for now. And they are bound in a strategy that is based on a five-year Parliament.
Five years for Nick Clegg to show voters that the Lib Dems are a responsible party of government that has made a difference to the lives of everyone by having their bums on cabinet seats.
Five years for David Cameron to get rid of the budget deficit and point the economy towards the sunlit uplands.
The question is whether they can stay the distance.
The danger will come from personality clashes and policy differences that become irreconcilable or an electoral disaster that threatens the very existence of the Liberal Democrats if they remain in coalition.
But we are not there yet, not by a long chalk.