Here's what I'd do in your situation, Ric.ror:
1. Find out the name and address of the property owner by forking out three quid here:
https://eservices.landregistry.gov.uk/eservices/FindAProperty/view/QuickEnquiryInit.do
2. Write to the property owner, roughly as follows:
"Dear Mr Bloggs,
I understand, from Land Registry records, that you are the owner of 21 Acacia Avenue, Sometown, which I further understand is currently occupied by rental tenants.
Should you be considering the sale of this property, I would be pleased to make you an offer for it thus, hopefully, enabling you to effect a quick sale and also allowing the current tenants to remain in their home.
I look forward to hearing from you.
Yours faithfully"