In 1941, aged 19, she joined
Bletchley Park as a decoder. Her father, himself involved in intelligence, recruited her. She spoke fluent Italian which led to her joining the
RAF section. She was billeted in nearby Fenny Stratford. Colchester entered one of “Britain’s most secret organisations”, Bletchley Park. The majority of Bletchley Park “was based on the forensic decrypting and ordering of thousands of enemies messages”. Colchester played a massive role in the “decrypting and ordering” of the enemy's incoming hand-encrypted messages, along with many other women working alongside Colchester at Bletchley Park. Due to Colchester’s past experience of decoding skills, this helped in uncovering many of the “general patterns of communications and confirmed logistical information”. She personally decrypted a high-grade Italian cypher overnight in 1943, which uncovered that the Italian air force was going to leave Tripoli that morning at 4am to bomb Sicily. Due to the intelligence, Allied forces were able to shoot down the bombers before they launched their assault. She also said that "it was so intense. There were such a lot of very clever and eccentric people shut away in the strange isolation. I remember
Alan Turing, he was very shy and awfully sweet. We used to have coffee after lunch in the canteen". After the war, she worked for the
Secret Intelligence Service in an undisclosed role. She served in
Cairo and
Istanbul where she helped investigate the double agent
Kim Philby. ==Personal life==