Brownism has two main strands: social injustice and inequality, and Britain’s place in a globalised world. Noting how every year Britain adds 75,000 engineers and computer scientists, while India and China add half a million, he argued: “Economies like ours have no choice but to out-innovate and outperform competitors by the excellence of our science and education, the quality of infrastructure and environment, and by our flexibility and our levels of creativity and entrepreneurship.”

There are echoes of the debate a century ago over “national efficiency”, which, after British reverses in the Boer War, reflected a concern over the condition of the poor and new economic challenges from overseas. That fuelled Joseph Chamberlain’s demands for protection, though Mr Brown retains strong free-trade instincts.

The conclusion, both then and now, has been that an active State is needed both to relieve poverty and to help people to prosper in face of intensified competition. An active State means not just higher public spending, but also myriad initiatives to change people’s behaviour: to encourage us all to improve our levels of skills, to live in zero-carbon homes etc.

Mr Brown’s earnestness was also meant to differentiate him from David Cameron and George Osborne: the serious and experienced man of office versus frivolous and inexperienced opposition politicians who do not understand how to tackle the new global challenges.

This tactic could rebound if “time for a change” trumps “familiar and tired”.

The prime minister in-waiting also sought to contrast himself with the Tories on spending and taxation. Mr Brown highlighted big increases in total capital investment, from £39 billion last year to £60 billion in 2011-12, with a large rise on the infrastructure of schools, colleges, and universities. He rejected what he called a third fiscal rule — the unstated Tory one of “sharing the proceeds of growth between spending and tax cuts” — which he claimed would require a cut in spending of £28 billion this year alone. So his mantra was investment in education, not tax cuts.

Much of this is, of course, baloney. The real gap between the parties is small, at least in the short term. The Treasury’s assumed annual increase in spending after 2008 will be only about 2 per cent in real terms, less than the underlying growth of the economy.

Moreover, Mr Brown is more cautious than his rhetoric. His backing for the Stern report on climate change is very guarded.

The increases in air passenger and fuel duty reverse recent erosions in their real value. But Mr Brown will not be rushing to introduce new green taxes, relying more on international agreements and the encouragement of carbon saving in new homes.

So while Mr Brown wants to place Labour as pro-public services against tax cuts, he wants to avoid an image of favouring higher taxes. Admittedly, yesterday’s measures will add £2 billion to tax receipts. But the overall tax burden is projected to stabilise at about 38 per cent of national income from next year onwards, after rising steadily in recent years.

This is a complicated exercise. Despite all the familiar, reassuring words about continued economic growth, and staying within the fiscal rules on borrowing, the margin for manoeuvre is tight. Mr Brown cannot, and does not intend to, raise public spending very much, because he fears being depicted as a high taxer. This headmaster wants to be re-elected.

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