You should file a 'notice of disassociation' with the credit reference agencies. You can do this online (for free) on the Experian website:
http://www.experian.co.uk/contactforms/consume r_onlinedisassociation.html
The credit reference agencies usually share such information but, for a 'belt and braces' solution, you should also complete the Equifax form. It's on a 'secure' web page, so I can't link directly to it. Instead go here
https://www.econsumer.equifax.co.uk/consumer/uk/sitepage.ehtml?forward=gb_cpo_faq
and click the 'here' link under 'Why
(sic) do I do if information for other people appears on my credit report?'
The last of the 'big three' credit reference agencies is CallCredit. Their form isn't available for online submission but you can download the form here
http://www.callcredit.co.uk/download/Disassoci ationForm.pdf
and then post it to them.
Incidentally, the credit reference agencies are not permitted to base credit ratings solely on someone's address (so you shouldn't really be having this problem). However, if (for example) you share a common surname with the previous occupants (or with someone with whom they had a financial connection) the agencies can assume that you're connected with them until you tell the agencies otherwise.
Chris