.htaccess and Rails direction


I'm having a bit of a battle with NativeSpace who are hosting my rails

Having had to downgrade from Rails 3.0.0.rc to 2.3.8 and then finding
that I was having major issues with that version and Mongrel 1.1.15
I've had to go back down to 2.3.5!!!

Now I have the following in my .htaccess:

RewriteEngine on

RewriteCond %{HTTP_HOST} ^worldtripper.co.uk$ [OR]
RewriteCond %{HTTP_HOST} ^www.worldtripper.co.uk$
RewriteRule ^/?$ "http\:\/\/enigmahostingcompany\.co\.uk\:
12004\/" [R=301,L]

RewriteCond %{HTTP_HOST} ^worldtripper.co.uk$ [OR]
RewriteCond %{HTTP_HOST} ^www.worldtripper.co.uk$
RewriteRule ^/?$ "http\:\/\/127\.0\.0\.1\:12004%

Which is not working ... and apparently it's "my problem" to resolve.

When I type www.worldtripper.co.uk ... I'd like it to stay that way
and the "transparent redirect" to be just that ... transparent. But
it's not ... it's changing to enigmahostingcompany.co.uk:12005/ which
is not ideal.

Does any one have any ideas on how I can get this to work ...

Or is it a problem with Rails?

I've been going at this for days .. and I'm not getting far! But it's
sooooo close ... it's frustrating!

Thanks in advance