The UK's largest law firms saw fee income rise by 6.3% during the 2014-15 financial year, according to new research from professional services firm Deloitte.

The organisation's latest quarterly legal sector survey found revenue across the largest 100 firms climbed by 6.7% over the quarter running to the end of April, taking full-year growth to 6.3%.

The average masks significant differences across the group, with the strongest performance coming in the firms ranked 11-25 and 26-50 by revenue, where annual fee income growth stood at 4.4% and 6.9% respectively.

Results for the larger firms were heavily affected by currency fluctuations and the strength of sterling against the euro, with Deloitte declining to provide figures for this group as a consequence.

The research found that within the 11-50 group revenue growth was largely achieved through increases in fees per fee earner of between 3.6% and 3.7%. Across the top 100 as a whole, fees per fee earner rose by a more modest 2%, with those lower down the rankings seeing growth driven by consolidation against only a 1% increase in fees per fee earner. There was a small rise in chargeable hours across the group as a whole.

The findings, which saw respondents forecasting fee income growth of 5.3% for the 2015-16 financial year, come as several early movers have announced positive results for the most recent financial year including Fieldfisher, Berwin Leighton Paisner and Addleshaw Goddard.

Commenting on the results, Jeremy Black, a partner in Deloitte's professional services practice, said: "Firms that focus predominantly on the London market generally outperformed both those with a more international focus and those focused on UK markets outside London.

"Firms with a more global footprint have faced a particularly challenging year, with the economic environment in certain overseas jurisdictions proving especially difficult. The reduction in the sterling/euro exchange rate has also put further pressure on results.

"Overall though, if you look at the wider economy, the legal sector has outperformed that – it's been a solid year."