File does not exist: /home/autobahn/public_html/500.shtml, referer: xxx/administrator/index.php?option=com_installer&view=install
This is the only message that was in the server error log - I checked at the time. The only other message was in respect of the favicon.ico file not being found.
Since I can't raise any kind of warning or error, have not been asked to complete registration and I've run all the Tools successfully as well I'm inclined to put this down to gremlins and to accept that the install was successful unless something else happens to indicate that it was not.
Many thanks for your help and time.