There is no mistaking it:

economic growth has finally returned. Even Shadow Chancellor Ed Balls has been forced to concede the point. The economy expanded by 0.8% during the first quarter of 2014, according to estimates by the Office of National Statistics, the fifth consecutive quarter of growth.

The International Monetary Fund, which last year warned the UK Government about the impact of its austerity policies amid talk of a triple dip recession, is predicting that the UK will be the world's fastest growing advanced economy this year. Chancellor George Osborne has pointed to growth in the key sectors of manufacturing, services and construction as proof that his strategy is working. So, does this amount to a vindication of his iron austerity?

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Not exactly. While there is indeed growth in those three sectors, and activity in manufacturing and construction in particular is encouraging, it is starting from an unusually low base. Manufacturing grew by 1.3%, its strongest quarterly performance for nearly four years, but remains 7.7% below its pre-crisis peak. Construction expanded by 0.3% during the quarter but is still 12.2% behind.

The UK economy still lags behind that of Germany and the United States in achieving its pre-recession levels. The suspicion that growth might have returned sooner without such punishing austerity is probably justified; not that the fact is likely to harm the Government very much now that a positive narrative is emerging from the economic figures. As TUC general secretary Frances O'Grady correctly notes, pay and job prospects remain below pre-recession levels.

With wage increases patchy and inconsistent, and with a long way to go to make up lost ground, higher consumer spending has come from debt and raided savings accounts, not wealth creation. Meanwhile, there have been ever louder warnings over the past month about a property bubble developing in the hothouse south-east of England. In Scotland, house prices in Aberdeen have shown almost 12% growth in the past year. Is this sustainable? Much of the activity is attributable to government schemes for first time buyers, which are commendable but could not be said to reflect strong underlying economic growth.

Still, the sense of energy in parts of the economy is undeniable, which begs the question of how this change will impact on the referendum campaign. Both sides wish to claim credit for it. While the Coalition at Westminster is trumpeting the latest figures as a success story of its making, the Scottish Government continues to blame it for having choked off earlier improvements with its austerity policies, while claiming credit for positive indicators in the Scottish economy. Whether a sense of growing optimism will encourage voters to back independence (especially if they think the recovery is south-east focused and makes a Conservative General Election win more likely), or convince them they are better off as part the improving UK economy, is a moot point. But it counts as one of the wildcards that could decide the vote.