During the years between World War I and World War II, British intelligence and security services made big changes to tackle the rising dangers from totalitarian governments like fascist Italy, Nazi Germany, and the Soviet Union. Here are some important developments:

1. Growth of Agencies:

   • MI5 (the Security Service) and MI6 (the Secret Intelligence Service) grew their operations.
   • MI5’s budget jumped from £10,000 in 1914 to £300,000 in 1935. This showed that people were starting to understand the risks of spying.

2. Fighting Spying:

   • MI5 concentrated on stopping spies and had over 300 officers working by 1939.
   • They kept an eye on groups that could be a threat, like the Communist Party and different fascist groups.

3. Watching and Collecting Information:

   • They increased their monitoring of political groups, which helped them gather important information.
   • By 1938, MI5 had records on about 30,000 people believed to have communist or fascist beliefs.

4. Laws for Action:

   • The 1920 Defence Act and the 1939 Regulations from the Emergency Powers Act set rules for detaining suspects and keeping an eye on them.

5. Working Together Globally:

   • British intelligence made strong partnerships with groups like the French Deuxième Bureau to share information about dangers coming from totalitarian countries.

These changes showed that Britain was taking steps to protect its democracy during a time when authoritarianism was growing across Europe.