Agree totally with Kath. Touch not one blade of grass until every last unoccupied house, shop and brownfield site has been utilised. Force these wretched people to do something about their properties. I did many years ago with the ghastly Dover Bargain Centre in London Road, now the immaculate Paint & Decor Centre. A post on Dover Forum attracted the enthusiastic support of the Dover Express and the rest is history.
To give a single instance out of many, how is it that some execrable property developer was allowed to purchase the old Army Recruitment site on Townwall Street and then permitted the buildings on this historic site to decay into near ruins? This was part of the Royal Naval Air Service seaplane base in WW1 and part of the Guilford Battery prior to that. Quite apart from its historic relevance, it would have made a superb home for somebody. As it is, the unscrupulous developers are believed to be holding out for an asking price of ten times what they paid for it, see Jeff Howe's article in the thread below.
http://1914-1918.invisionzone.com/forums/index.php?showtopic=105582&st=25