I didn't realise that. Is it the same for each area? I thought rates have always payable after a certain empty period...
Edit
"You pay no business rates for the first three months that the property is empty. This is extended to six months in the case of certain industrial properties. After this period, rates are payable in full (100%). However, listed buildings and small properties with rateable values of less than £18,000 pay no rates at all, even after the first three months.
Empty property relief is available to the owner - in this case the owner is the person entitled to possession of the property in question."
http://www.lichfielddc.gov.uk/site/scripts/documents_info.php?documentID=94&pageNumber=3
It has been like that as long as I can remember. Lord knows how landlords can afford to leave large industrial units empty for years on end and not want to negotiate on the rent??!