The county council have got back to me.....
‘Not our problem, district Council or police’
Sorry for missing that "Cambs CC" in the opening post meant Cambridgeshire County Council and not Cambridge City Council. The county council are arguably correct: while highway defects are a county council responsibility, highway obstruction is a police responsibility, while parking offences (in many places and I think Cambridge) and illegal dumping are the city council's problem.
This is why I use
www.fixmystreet.com because it does better than me at directing problems to the correct body at the first attempt. I think it still stuffs up when it's Highways England's responsibility, though.
Of course, the ***** council should just pass the report on to the city council, instead of leaving you to start all over again, but they won't. Welcome to patchwork government. Party like it's 1974!