Sorry to bring this post up from the dead, but there is a way that you can still use the URL http://www.addiscombe.org/members/phpBB2/ without having to put the index.php in.
Open the Apache folder and open the httpd config file.
Add
[code]#
# DirectoryIndex: sets the file that Apache will serve if a directory
# is requested.
#
<IfModule>
DirectoryIndex index.php index.php4 index.php3 index.cgi index.pl index.html index.htm index.shtml index.phtml
</IfModule>[/code]
This should do the trick.
If not, drop me an email and I'll help you out
James