Thanks both of you. Yes i see that after a little time, the home.css file worked, so it was probably some kind of caching issue as well. I had thought that maybe the behavior had changed in different versions of DNN but it looks like it works the same.

Another thing I noticed in the process, is that the 'mynewskin.css' file (matching the name of the .ascx file) will also work if placed in the portal folder (/Portals/1/mynewskin.css) . This one will override the one in the main skin folder.

I had thought that maybe this was written into the ascx file itself, but it looks as though it is built in to the code behind somewhere..

Thanks for helping me to understand this. Much appreciated

Tom