He joined the Komsomol in 1923, using his Communist Party affiliation to gain an education. Through this education he was able to do well enough on his naval recruiting tests to become specially selected for the cipher-work training course. After the two-year technical course which qualified him as a cipher specialist, he was posted to a ship in the Baltic Sea to encrypt and decrypt the secret signals.
Petrov miraculously survived the purges of Stalin under Yagoda, Yezhov, and Beria. Even though he saw and heard of the great of number of his friends, colleagues, superiors, and famous revolutionary characters who were being arrested and executed, Petrov escaped unscathed.
Vladimir Petrov applied for political asylum in 1954, on the grounds that he could provide information regarding a Soviet spy ring operating out of the Soviet Embassy in Australia.
Petrov states in his memoirs (ghost written by Michael Thwaites) that his reasoning for defecting lay not in an imminent fear of being executed, but in his disillusionment with the Soviet system and his own experiences and inside knowledge of the terror and human suffering inflicted on the Soviet people by their government. He was there to witness the destruction of the Siberian village in which he was born, caused by forced collectivization and the famine which resulted. He remembered the blacksmith who taught him of the virtues of Communism and who also got him started in his education. This blacksmith was labeled a kulak and forcibly deported with his entire family, probably to die. Petrov learned the true excesses behind the Great Purges while decrypting signals which set quotas for the murder of citizens.
The whereabouts of the Petrovs was still the subject of a D Notice in 1982.