However, the Euromoney report shows that, despite the level of fees, London remains more important as a legal centre than any other European capital.
According to Euromoney, which compared legal services in 15 European countries, companies pay an average of pounds 140 an hour for advice on domestic British law and pounds 231 an hour for advice on international law.
This is significantly more than is charged by lawyers across the countries surveyed, assessed by Euromoney at an average of pounds 166 an hour. The average fee for domestic legal services was pounds 134.
British lawyers charged more for advice on international law than their colleagues in any of the other 15 countries. On domestic matters, only German, French and Swiss lawyers were more expensive than the British.
In-house lawyers employed by large UK companies tended to earn slightly less than their counterparts in the other countries. The average salary in Britain was pounds 54,000, with earnings ranging from pounds 35,000 to pounds 97,000. On the Continent, salaries ranged from pounds 37,000 to pounds 101,000, with an average of pounds 58,000.
However, clients considered fees less important than technical ability, knowledge of the law or understanding of the market. Cost was only the seventh most important factor when chosing a law firm.
Euromoney asked 185 of the biggest companies in Europe to list their top law firms, and the results served to emphasise the pre-eminence of London. Of the five best firms, four are based in Britain - Clifford Chance, Linklaters and Paines, Slaughter and May and Freshfields.
'The survey shows that London is still Europe's dominant legal centre, with strength in depth unrivalled anywhere on the Contintent,' the report says.
However, it adds: 'Dutch, US and German firms are fast challenging UK firms' dominance of Europe, constituting six of the top 10 best law firms.'
Three-quarters of respondents said they would need more legal advice in Eastern Europe, but could not find lawyers proficient in the field. This was one of 'several important new challenges' facing corporate legal departments, Derek Duggan, research manager at Euromoney, said.