Back in the dark ages, oh, a decade or two ago, Autumn Statements were dull affairs – the Government’s opportunity to update the economic and fiscal numbers six months or so after the Budget.

If Philip Hammond has his way, the Autumn Statement might go back to being a bit like that in future – but this year’s event promises to be a major one.

In large part that’s because this is the first fiscal event since the Brexit vote in June.

Having eschewed the opportunity of holding an emergency Budget in the summer, Mr Hammond has a lot to cover.

On that basis, and the basis that events like this are stuffed with an overwhelming amount of detail (some important, some extraneous), here are the five most important things to look out for.

1. What are the new growth forecasts?

While all the papers seem most obsessed with the question of how much the Chancellor will be giving away (spoiler: not much), this question – how strong and resilient the economy is – is probably the most important one of the entire event.

After all, if the Office for Budget Responsibility (OBR), which calculates the official government growth numbers, thinks the economy is heading for the sink, that will mean much less tax revenue, and much less money for the Chancellor to give away in future.

Back in the Budget, the OBR expected GDP growth of 2.2% next year and 2.1% the following years. Those numbers will probably be cut to 1.5% or below in the coming years.

That is part of the explanation for why the Government will have to borrow more – potentially £100bn more – over the coming five years. And that’s before you consider whether it wants to spend a bit more, which brings us to question two.

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2. How much of the extra borrowing is down to Brexit?

Because the chances are the majority of the increase in borrowing will not be down to any Government-planned splurge.

Yes, there are likely to be some small measures designed to help struggling families. But add them up and they are likely to look piddling in comparison with the likely increase in the deficit caused by those OBR forecast changes.

True, there’s a significant chance the OBR is wrong and is too pessimistic, but there are few forecasters who expect stronger growth in the coming years, such is the concern over those Brexit negotiations.

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3. What are the new fiscal rules?

As you probably know, George Osborne’s three fiscal rules (1. Get a surplus, 2. Cut the national debt, 3. Cap benefits payments) are all now kaput.

Mr Hammond is expected to replace these rules with a new set. The chances are his framework will look a little like the one Mr Osborne had in his first parliamentary term – a goal of eliminating the budget deficit, but allowing for extra spending on investment.

That would give the Chancellor room to spend on new roads/railways/broadband without busting his rule. There will also be a time-limited rule on getting the national debt down, and perhaps some other little bells and whistles.

But the one thing we know for sure is that, sooner or later, the rules will be broken. They almost always are.

:: Hammond plans to spend £1.3bn on road improvements

4. How vague will the OBR be about the costs/benefits of Brexit?

Actually, the OBR’s job is not just the most important but arguably the trickiest in the run-up to this Autumn Statement.

After all, it has to make all sorts of judgements about how those Brexit negotiations will affect the UK economy while remaining as much in the dark as the rest of us about what will actually happen in those negotiations.

So keep a close eye on the provisos it adds to its forecasts about how sure it can be. The chances are it will say the level of uncertainty over the forecasts is greater than ever.

It might also have to be vague, too, about what happens to the UK’s EU contributions in the future.

While you might have assumed that once Britain is out of the EU it won’t have to pay the £10bn or so it contributes (in net terms) to the EU budget, the reality may well be that, depending on the eventual deal, the UK does eventually have to contribute at least something.

:: UK is in Brexit vote lull before economic storm, warns Alistair Darling

5. What about all those manifesto pledges?

Remember the Conservatives committed themselves to a lot of quite expensive policies in their manifesto – policies many in the Treasury would rather like to wriggle free of.

So keep an eye on the following promises: do they get fulfilled, forgotten or even reversed?

:: The triple lock under which the basic state pension is increased by either inflation, earnings or 2.5% – whichever is highest.

:: To increase the tax free allowance to £12,500 for basic rate earners and to £50k for higher rate taxpayers

:: To spend 0.7% of GDP on international development

:: To freeze commuter rail fares for the entire Parliament

These questions should help you navigate the day – as will one big overarching question, the one I always ask myself whenever the Chancellor announces something very exciting-sounding: is this really new, or is it yet another reannouncement?

:: Watch full coverage of the Autumn Statement on Sky News on Wednesday from 10am.

(c) Sky News 2016: Autumn Statement 2016: Five big things to look out for