The Autumn Statement saw the Chancellor introduce new fiscal rules which offer a lot more wiggle room. But while he used some of this leeway to increase infrastructure investment, the package was relatively small and is unlikely to have a material impact on the outlook.The OBR surprisingly waded into the Brexit debate by offering its estimate of the impact of Brexit on growth and the public finances. But in our view its methodology was fatally flawed, so the results of the exercise were virtually meaningless.