The years immediately after the First World War saw MI5's size being reduced drastically as a result of post-war cost-cutting. The Service's very existence came under threat for a time, but by the start of the 1930s it had gained new importance in countering communist and fascist subversion in the UK. It also played a leading role in countering Soviet espionage and obtaining information on Nazi Germany.
The inter-war years
MI5's fight for survival after World War I and its penetration of Nazi Germany's London embassy
The Soviet threat between the wars
How MI5 countered Soviet intelligence activities in the UK
On 9th November 1989 the Berlin Wall fell - one in a series of monumental events that went on to transform Europe, and...