Thanks, Mary, but I am familiar with that - and that is what I need an answer to change.
As explained, I need to have myself able to read/write, a selected group to be able to only read and the rest of world to be unable to access at all.
As also said previously, I'm going to try Stefano's response... and in case that fails then I've been reading up on Linux and found things like 'chmod', 'chgroup', 'chusr' that I should be able to use to alter permissions on the folders at the OS level???
Might need to set up a new SME Server just to play about on though....
Cheers
Steve