Historians are already asking for more, and MI5 is expected to release files on the Second World War next year, but the internal security branch of Britain's spy services has refused to release docu- ments from the interwar period.
This has disappointed academics who claim that this is the most interesting era. Professor Bernard Porter, head of history at Newcastle University and a secret service expert, says: "The later period has been pretty worked over already, whereas the 1920s and 1930s are much darker and also more controversial."
But he is impressed that MI5 is opening up records it was thought would never be revealed, and believes greater openness will promote greater confidence in the present organisation. "Trying to get through in the past has been like writing to Father Christmas."
The released archive reveals a devastating blow to the Kaiser in August 1914 when 21 of his spies were arrested. It was a dismal failure for the German espionage effort. None of the agents succeeded in learning any secrets and 11 were executed in the Tower. But it was Special Branch, not MI5 who traced the spies to a barber's shop in north London.
Germany began spying on Britain in 1904, and very inefficiently - witness the agent stationed at a port who flew a German flag on his houseboat, and asked questions about guns in a heavy gutteral accent.
Many personal details also appear in the archive, including the diary of the first director general, Sir Vernon Kell, and Melville, the first recruit: he and an agent named Drake discovered 36 spies before the war.
Other details include the news that lemon juice was used for secret writing until a chemical alternative was discovered, which also doubled up as a cure for VD - a vital travelling companion for any gentleman, it was said.Reuse content