Britain won backing from its European Union partners on Monday to prevent parts of its financial services sector potentially having to relocate to the
euro zone.
Britain is already taking the European Central Bank to the bloc's highest court for its policy of requiring clearing houses which help process a significant amount of euro-denominated transactions to be based in the single currency area.
London-based LCH.Clearnet is a major clearer for instruments denominated in euros.
On Monday, EU ambassadors formally endorsed a preliminary deal they reached last Thursday on updating the bloc's MiFID securities trading rules to take into account advances in technology and lessons from the financial crisis.
Britain, as part of agreeing to that deal, called for a new clause to be inserted and this was backed by ambassadors at Monday's meeting.