Here's teh steps taken so far
1. In the iTunes Music folder I've deleted those I don't want any more and removed duplicates.
2. Next I copied all the music (app 47 GB) onto an external drive and deleted all the music in the iTunes Music folder.
3. I copied all the Artist folders back from the ext drive to User/Music/iTunes/iTunes Media/Music.
4. I've gone into iTunes preferences and set the location of the Media to User/Music/iTunes/iTunes Media and restarted iTunes. Not successful and I wonder if I should point it to User/Music/iTunes/iTunes Media/Music ?
I've checked Keep iTunes Media Organised in preferences but fear duplications again so haven't selected Copy files to media folder when importing to Library.