Readers will almost certainly know about the history of how Berlin evolved after 1945, but a very brief summary. The city was divided into four sectors: British, French, US and Soviet. The first three then became ‘West Berlin’ and the Soviet sector ‘East Berlin’. During the early period, there was the famous ‘Berlin Airlift’ for eleven months in 1948/49, when land connections to West Berlin were severed by the Soviets before matters returned to normal. But later, overnight on 12/13th August 1961, a barbed wire fence went up around West Berlin, effectively making it an island within East Germany (DDR). This fence soon became a much greater barrier, involving a mixture of high walls and/or fences, mines, self firing guns, dogs and frequent watchtowers with armed guards. Known officially in the DDR as the ‘Antifascistischer Schutzwall’ or ‘Anti-Fascist Protection Barrier’, its objective was simply to prevent people fleeing to the West.
In West Berlin in the 1970s, the modes of rail transport were: U Bahn (underground), S Bahn (overground suburban) and the Stadtbahn (main West East main line) from West Germany to Berlin and then further East to Warsaw etc. The U Bahn in West Berlin was then controlled by West Berlin authorities, but the S Bahn and
