I am still confused! If I own ivestment properties, rely the tenants are resposible for the higher council tax bills? I can see it affecting the affordability from the tenents point of view and indirectly affecting the market (and maybe myself?) Please advise if I have this wrong.

Got it in one Chris. Actually, the tenants are only liable while they are in occupation - which means, sadly, you will become liable for the void periods. Many local authorities are using their discretion to inflict instant 'empty' rate taxation on all 2nd home owners, including investor landlords. The new proposals will probably be inflicted in the same way, but at twice the cost. It is therefore even more important to try to keep voids to an absolute minimum, to protect annual yields.