Gordon Brown, the Chancellor, received a welcome present on his 55th birthday today as official figures showed that Britain's budget surplus hit a record high of £15.3 billion in January.

The figures on the state of the public finances, published by the Office for National Statistics, come just weeks ahead of Mr Brown's Budget in March, which some political observers have suggested could be his last as he gears up for a potential Government leadership campaign.

City economists said the figures - which came thanks to a 50 per cent surge in corporation tax receipts - mean the Chancellor now has a "realistic chance" of hitting his revised public sector borrowing target of £37 billion and maintaining a current budget deficit of £10.5 billion.

Moreover, experts said the renewed strength of the public coffers makes it almost a racing certainty that Mr Brown can steer clear in his March Budget of the kind of big tax rises or significant spending cuts that would probably make him highly unpopular with the electorate.

Howard Archer, the chief UK and European economist at Global Insight, said: "The strength of the public finances in January effectively guarantees that Mr Brown will be able to avoid making any major tax hikes or significant spending cutbacks in March's Budget.

"Furthermore, Mr Brown had already alleviated the near-term pressure to tighten fiscal policy to meet his "Golden Rule" [of balancing the budget over the economic cycle] by moving the goal posts yet again in December with a further extension of the economic cycle."

Simon Wallace, an economist at the Centre for Economics and Business Research, added: "Gordon Brown will be blowing his candles out with extra gusto today as United Kingdom public sector net borrowing fell to -£12.6 billion in January 2006 - down from +£6.5 billion in December, and below the January 2005 figure of -£3.7 billion.

"This figure exceeds all market expectations, well below the forecast level of -£7.8 billion."

Mr Wallace pointed out that January is usually a "good month" for the Treasury in terms of tax-gathering. But nevertheless, he noted that: "This month sees the budget move into surplus for the first time since October 2005 and is up £3 billion (25 per cent) on January 2005. The Chancellor has not seen a surplus like this since the first quarter of 2001.

"One must remember that these are only the figures of a single month – but as Gordon Brown prepares for what could be his last budget in March 2006, he will be sleeping a lot easier. There is no longer the same pressure to cut spending or raise taxes."

According to ONS, the public sector made a record net cash repayment of £21.1 billion in January, meaning it needs more than £1 billion less cash between now and the end of its financial year in April than it did in 2005.

Public sector net debt, as a percentage of GDP, stood at 35.6 per cent in January, up on the 34.1 per cent recorded at the same time last year. However, Mr Brown's forecast in the Pre-Budget Report for net debt of 36.5 per cent of GDP as at the end of March.

Total net debt was £442.7 billion at the end of last month, ONS said, which is just under £36 billion less than at January last year.

But despite the good news on public sector finances, City experts still warned Mr Brown that he might struggle to achieve his fiscal objectives for the financial year 2006 to 2007.

"Consequently, we believe that significant fiscal tightening measures could yet be enacted in 2007, unless faster than expected growth rides to Mr Brown's rescue," Mr Archer said.

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