Hi Graham,
The smaller profile is empty of emails/items, just some empty folders.
I did as you suggested, but when I tried to change the big pst to default, it came up with a warning screen
"the default outlook data file contains the calendar that appears..."
I googled on that, and it said to ignore it, and it seems to have worked.
So now all need to do is backup one PST... yippee!
I think that is all - thanks, Sid