The Berlin Wall, constructed in 1961, was a concrete border separating West Berlin from the eastern sector of the city.  It was built to stop the flow of emigration from the east to the west, and was also intended to curb the rampant black market activity that threatened the economy of the German Democratic Republic (GDR, East Germany).  

Arc lights were mounted on watch towers at frequent intervals along the Wall, and a 30ft-wide strip of land on the eastern side came to be known as the ‘death strip'.  A shoot-to-kill policy for East German border guards made unauthorised attempts to cross the Wall extremely dangerous.  Between its construction and its fall in 1989, about 5,000 people successfully escaped from East Berlin, although others lost their lives in the attempt. The number of deaths is disputed but ranges from 90 upwards.

Today, many see Israel's much longer and higher West Bank Barrier as politically and morally comparable to the Berlin Wall.

In John Le Carré's espionage novels, the British Secret Intelligence Service is headquartered at Cambridge Circus in London, where Shaftesbury Avenue and Charing Cross Road meet. For this reason, the HQ is known throughout his novels as "the Circus".  Whether or not the author intended this nickname to be a wry comment on the smooth and efficient running of British Intelligence is unknown.

In real life, SIS (also known as MI6) was at the time of this novel based in St James's Street and Broadway, moving in 1966 to Century House in Lambeth. It now occupies a rather grander headquarters at Vauxhall Cross.  All that you're likely to find at Cambridge Circus is the Palace Theatre and a lot of traffic.

 

Just as Britain's SIS becomes "the Circus" in John le Carré's fictional world, so the GDR's Ministry for State Security, or Stasi, becomes "the Abteilung" (the German word simply means "department").

Anna Funder's book Stasiland is a journalistic examination of the infamous instrument of state repression and counter-intelligence.

Stasiland on Book Drum

The Lives of Others presents a superb cinematic portrayal of the Stasi's spying on its own citizens.

             

A reference to Agatha Christie's 1939 novel in which ten characters are killed off one by one.  The book, later retitled And Then There Were None, drew its original title from a nursery rhyme which in turn derives from an 1868 song called "Ten Little Injuns":

Ten little Injuns standin' in a line,

One toddled home and then there were nine;

Nine little Injuns swingin' on a gate,

One tumbled off and then there were eight...

and so on...

Listen on Spotify: Ten Little Indians performed by Harry Nilsson

     

This was the Rotterdam Blitz of 14 May 1940, when the German air force mounted a fierce aerial bombardment of the city to support their ground troops and break Dutch resistance, forcing the Netherlands to surrender.

Alec Leamas spent part of World War II in Holland.