The City's top law firms have won a major battle in their quest to overhaul conflict rules, it has emerged, after the Law Society agreed to make it easier for advisers to gain consent to take on potentially conflicting roles.

The Law Society's ethics committee last week agreed to amend guidance on its conflict rules to allow firms to obtain upfront client consent through standard engagement letters.

The move, which would require firms to erect information barriers and would still bar advisers from acting for opposing clients on a related matter, is regarded as a major victory for the group of top City firms that have lobbied on the issue.