Thanks Donoreo, I will take a look at your suggestions. However I did pick up the latest edition of PhotoPlus which arrived yesterday and looking through it again realised it was in there I had seen it .
In the sidebar on p75 under "Incremental Back-up" Peter Travers had given details for a free download called FILE SYNC at
http://filesync.moleskinsoft.com which apparently "
automatically analyses folders and copies only new and modified files. It works effectively with large numbers of files within multiple nested folders,making subsequent incremental back-ups much quicker and easier to carry out"
Now where did I put that magazine?

Dagwood