http://www.economist.com/blogs/newsbook/2010/07/artview_0.

“Competition between dealers and the auction houses for art works and clients is fierce. But sometimes cooperation can have advantages. Two big events, Master Painting Week and Master Drawings London, are now taking place in London, coinciding with the important Old Master Paintings and Drawings sales at Christie’s, Sotheby’s and Bonham’s. This is no accident: London is the Old Master capital of the international art world, and by working together to attract collectors, curators, museum trustees and, indeed, potential vendors to the city, the dealers and auctioneers will help keep it that way.”