... follow up from my prevous post I've got a final reply from the 'other' hosting company:
Dear Paul,
Thank you for your email dated the 29th April 2008.
Unfortunately a PTR record is something that is not provided with out
VPS Hosting servers, however other hosting companies may provide a different service.
I hope this provides you with the information you require.
if anyone else is looking for hosting check you have the facility to set up an rDNS PTR record - if not avoid like the plague!!