A search of various Council websites all make the same statement word-for-word on this issue:
Council tax penalties
"We have powers to impose penalties where a person is required by law to provide information (for example, to enable us to work out who should pay council tax) and either fails to do so, or supplies information which the person knows is false".
Now, what that law is, I don't know; but it looks pretty clear that you're fighting a losing battle. But you might want to troll through the OPSI website to try and find it.
http://www.opsi.gov.uk/acts.htm
From what I've been able to find out, the tenant is obliged to pay Council Tax before the landlord since they occupy the property. So, even if the landlord/tenant agreement was silent on the issue, the Council would bill the tenant. But if they can't find out who the tenant is and the owner doesn't tell them, then not only is the lanlord liable for the tax, but the council can also impose a penalty in addition to the tax.
So you either say or you pay!!