(Reuters) - Britain's economy is bigger than previously estimated and stood at 2.7 percent above its pre-crisis peak at the end of the second quarter, according to new official figures on Tuesday.

The data from the Office for National Statistics, which reflect new methods of calculating gross domestic product (GDP), and showed Britain's economic output exceeded its peak before the 2008-09 recession in the third quarter of 2013.

Previously, it was thought Britain achieved this only in the second quarter of this year, when it was estimated to have exceeded the peak by just 0.2 percent.

The new estimates are part of European Union-wide changes to national accounts designed to better measure the size and scope of its economies, coupled with other adjustments made by the ONS.

The data are likely to be welcomed by the Conservative-led government ahead of a national election next year, although it showed they showed the economy grew 1.7 percent in 2013 -unchanged from the previous estimate.

The ONS also said Britain's gross domestic product (GDP) grew 0.9 percent on the quarter in the three months from April to June this year, a slight increase from 0.8 percent.

That compared with 0.7 percent growth in the first quarter, a slight downward revision from 0.8 percent previously reported.

GDP was 3.2 percent higher than in the second quarter of 2013.

Output in Britain's services industry expanded 1.1 percent in the second quarter, the fastest growth since the third quarter of 2011. Construction was revised up sharply to show 0.7 percent growth, compared with a previous estimate of no growth.

Economists had expected both rates to remain unrevised to show a 0.8 percent rise on the quarter and 3.2 percent on the year.

The new methodology includes major changes such as treating corporate research as output rather than a cost, as well as some more eye-catching additions - like estimates of the activity of prostitutes and drug dealers.

Recent business surveys suggest the momentum behind Britain's swift economic recovery will carry through to the final months of this year.

British consumer morale edged down this month, albeit only slightly from a recent nine-year high, a survey from researchers GfK showed on Tuesday.

The Bank of England forecasts that Britain's economy will grow by 3.5 percent this year, which would be its best rate of growth in around a decade, given recent downward revisions to growth in the run-up to the financial crisis.

BoE policymakers are keen to see the recovery broaden from consumption and into investment - a key signal that the upturn will be sustainable in the long-term.

The ONS figures showed business investment rose 11.0 percent on the year during the second quarter, and 3.3 percent from April to June alone.

An ONS official said the growth rates were affected by the inclusion of research and development as an investment rather than consumption.

Household spending rose a quarterly 0.6 percent and real disposable income rose by 2.2 percent on the quarter from the previous three months. The savings ratio rose to 6.7 percent from 5.7 percent in the first three months of 2014.

The ONS revised Britain's budget deficit excluding banks for the 2013/14 fiscal year to 5.7 percent of GDP, compared with 7.2 in the previous year.

Public sector debt as a percentage of GDP, excluding banks, is now estimated at 79.1 percent, compared with 76.5 percent in July under the old methodology.

The ONS also released second-quarter current account data, which showed that Britain's deficit with the rest of the world widened to 23.1 billion pounds from 20.5 billion in first three months of 2014. That was equivalent to 5.2 percent of GDP, up from 4.7 percent in the first quarter.

Economists had expected the current account gap to narrow to 17 billion pounds.