Three years after European monetary union, euro notes and coins enter circulation next month. Some observers predict a mild boost for the currency. But will fresh impetus also be lent to Brussels’ initiative to build a single European market in financial services to complete the picture? This project has been caught up in a constitutional trial of strength as the Strasbourg-based parliament asserts itself. Alexandre Lamfalussy, an architect of the project, hopes the euro’s arrival will focus attention on resolving the dispute about who should agree the principles and who the detail.