So 20=Rochester then.
20- Chester.
Does the clue relate to the previous football club being City until someone screwed it up. The Phoenix club just being Chester?
stuving is correct. It's the signal box just outside Rochester station. So, sorry richwarwicker, no.
Rochester was a city from 1211 until 1998. It lost its city status due to an administrative error. It was four years until the error was discovered in 2002. The error came about when local government areas were changed.
http://news.bbc.co.uk/1/hi/uk/england/1991827.stmAttempts have been made by Rochester to recover city status, but thus far they've not been successful.
All that aside, and with apologies for the poor picture, it's an architecturally interesting signal box. A better view (not my own),
http://www.rail.co.uk/images/3105/original/rochester-signalbox-by-phil-marsh.jpg from the following web page:
http://www.rail.co.uk/rail-news/2012/southeastern-announces-may-timetable-alterations/