Sir John Buchanan, the Deputy Chairman and Senior Independent Director on the Vodafone board, is to retire after the mobile phone network giant's annual general meeting on July 24th.Following this change, Luc Vandevelde, former Chairman of Marks & Spencer and one of the world's most famous Belgians, will become Senior Independent Director of Vodafone.Buchanan joined the Vodafone board in April 2003. JH