Tara GreavesA map drawn up by Russian spies featuring Norwich is part of a new exhibition of previously classified documents.Tara Greaves

A map drawn up by Russian spies featuring Norwich is part of a new exhibition of previously classified documents.

Soviet cartographers were given the task of translating Norfolk place names for the map, which was produced during the Cold War era but we are left to wonder how they coped with some of the pronunciations - such as Costessey.

In 2007, the Evening News revealed how every building and site deemed to be of military and strategic importance in the city, including the Castle Museum and Norwich Cathedral, had been detailed in a map drawn up by the KGB, the Soviet Union's secret police, to guide Russian paratroopers and tank commanders in the event of an invasion.

The latest map is one of the recently declassified documents and other top secret material from the Cambridge University collection to be featured in a new exhibition showing the university's spy connections.

It includes student record cards for Kim Philby, Anthony Blunt, Guy Burgess and Donald Maclean who met at Trinity College in the 1930s and were recruited to pass secrets to the Soviet Union during the Cold War.

A letter from Winston Churchill, then Chancellor of the Exchequer, to Prime Minister Stanley Baldwin is also among the exhibits.

In the letter, dated in February 1925, Churchill is 'incensed' at being denied access to intercepted Japanese telegrams already seen by more junior personnel.

The letter reads: 'How can I conduct the controversies on which the management of our finances depends, unless at least I have the same knowledge of secret state affairs freely accessible to the officials of the Admiralty? The words 'monstrous' and 'intolerable' leap readily to mind.'

Other exhibits include a telegraph from the MI6 chief of the day confirming news of Rasputin's murder, papers used by a Parliamentary Committee investigating the Atterbury Plot of the 1720s and the Soviet map of East Anglia.

The free exhibition, titled Under Covers: Documenting Spies, at Cambridge University Library is now open and runs until July.