Four years ago Christchurch City Council vowed to get tough on the owners of 30 central city buildings left derelict since the 2011 earthquake. A wander through central Christchurch shows many of the buildings, nicknamed the dirty 30, still look unchanged. There are boarded up windows, tarps covering gaping holes, and containers keeping bricks from falling on passers by. But council says progress is finally being made on most Rachel Graham has more.