if you unclip the mirror flap you will find that inside you should have two spring clips and either one or both have been dislodged.(you may have to remove complete sun visor to recover them if they are still inside and have not been lost) clip them both back into place and hey presto.hope this helps. if you have lost the clips you will need to buy a new sun visor as jaguar do not sell replacement clips.
ben
December 2008