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Pundits and politicians like to set tests for Budgets.

They like to say a chancellor "has" to do this or that, they must "prove" they have the ambition to do this, to "deliver" on a party's manifesto promises, the list goes on.

But what do you do if you're the chancellor and you have no majority to speak of, not much money to spend within the rules you have set for yourself, and you work for a prime minister who doesn't have very much authority?

Simple, your biggest job is to avoid screwing up.

That won't be written on the first page of the chancellor's red book, or in the speech he'll carry in his red box.

But that clear and not necessarily very exciting goal will be hanging in the air in the Commons today.

Of course Philip Hammond won't admit as much, he won't stand at the despatch box and tell the country "listen, I am just for the next 40 minutes or so going to try to keep myself out of trouble".

And there will of course be decisions announced today that will have an impact on people's lives. There will be more money for the NHS, although not as much as they have asked for, there will be new policies to try to encourage house-building, there will probably be changes to universal credit, there will be measures that will make a difference to firms around the country.

But for the Treasury today there's no big bazooka - boring is good.

It is possible of course that the Treasury has simply been managing expectations. By leading people to believe there's not much to see, anything that seems a modest success might feel like a decent win.

But the first political responsibility of Number 11 today is to try to avoid mistakes. Inspiring? Perhaps not. Vital to the prospects for the government and Philip Hammond's career? Most definitely so.