Alan and Urs,

Thanks to your helpful comments I now have a backup running nicely
with an embedded server - and understand better what's going on :-).
In the end I used IBOAdmin components.

For anyone else who might be interested in getting the information,
I got IBOAdmin_d5.zip from

http://www.ibobjects.com/ibocontributed.html

where there is also a useful example:

BackupUnderEmbed.zip from Helen Borrie.

IBOAdmin_d5 needed a trivial bit of tweaking to run in D7.

Thanks to everyone.

Rob