George Osborne can on Tuesday prove that he is the right man for the toughest job in UK politics. That the shadow chancellor loves to cook “ham boiled in cherry cola”, the only memorable fact to emerge from a soft-focus interview before the biggest speech of his career, is little reassurance. Bond markets still know too little of how he would restore sanity to the public finances. They want red meat, dripping blood, not cherry Coke.

The 38-year-old may inherit a deficit of 13 per cent of gross domestic product, with a structural hole of £90bn. His formidable political brain calculated long ago that he was destined for unplumbed depths of short-term unpopularity – a worthwhile price for a reputation as the conviction politician who tamed rampant public spending. He might oversalivate in pursuit of a small state agenda. There is the spectre of 1937, when the US was pushed back into recession by premature tightening. But this danger should not be overstated. The real risk is bond markets push up borrowing costs on a public debt that by 2014 will have risen at the fastest rate of any G20 nation to reach nearly twice Gordon Brown’s 40 per cent golden rule limit. There is no room for prevarication. A third of it is foreign owned. Every percentage point rise in its cost adds £13bn in interest.