Thanks for all the help, unfortunately if I include only the above in an otherwise blank .htaccess file the server still returns a two step redirect. It first strips out the /index.php/ while retaining the old path and then redirects to the new url. Live HTTP headers say each step is given a separate 301, googlebot entries in my logs show the same.
I'll call the host once more, this isn't an htaccess issue anymore I don't think, at least not in my file. Sorry for the thread hijack!