Simplify the following text for a Grade 7 native English-speaking person.
Original: GCHQ was originally established after World War I as the Government Code and Cypher School ( GCCS or GC&CS ) , by which name it was known until 1946 .
Simplified: GCHQ was started after the First World War as the Government Code and Cypher School ( GCCS or GC&CS ) , by which name it was known until 1946 .