September's public borrowing figures, showing net borrowing of £8.1 billion and a cumulative April-September figure of £37.6 billion have attracted plenty of headlines. With six months of the fiscal year to go, Alistair Darling is already close to his £43 billion target. The question is whether the borrowing numbers will follow the usual "front-loading" pattern. The easiest thing with the public borrowing figures is to take the first six months and double it. Usually, that would also be the wrong thing to do.

In 2007-8, for example, net borrowing was £21.5 billion for the first six months and £35.8 billion for the full year. Scaling up, that would give a figure of £62.6 billion for 2008-9, based on the first six months. What we don't know is the extent to which the downturn/recession will affect that front-loading pattern.

Meanwhile, we have two figures for public sector net debt. Excluding Northern Rock is is a very respectable 37.9% of GDP. Including it, debt rises to 43.4% - still low but with other banking rescue effects to be added in.