Thanks, having wrestled with this all day I think I found two possible solutions. Yours and a plug in called FTP to media which bizarrely (after I had spent ages faffing about with filezilla) did not need ftp at all. I loaded the files into a wordpress media admin file on my server and then used the plug in to upload into the media library. Unfortunately somewhere along the way something else has happened which has stopped any changes on my site taking effect and so unable to test either. According to other searches this could be a full cache, but I have emptied my browser cache and it is still doing it. It is really one step forward and two back at the moment and I am starting to consider nuclear options of clearing everything and starting again
