Mr Doyle was not the only person to potentially sell inside secrets on the development of Concorde.
In 1999, it was revealed a spy codenamed “Agent Ace” had also betrayed Britain.
The agent was an aeronautical engineer recruited in 1967, according to papers smuggled out of Russia by dissident KGB officer Vasili Mitrokhin.
It is thought Ace handed over more than 90,000 pages of detailed technical specifications.
The agent was one of more than a dozen spies operating within Britain and passing commercial and technological secrets to the Russians at the height of the Cold War, the papers revealed.
The secrets that made it out of Filton helped Russia build the Tupolev-144, nicknamed Concordski, and which was strikingly similar to Concorde.
It remains unclear whether Mr Doyle did, in fact, pass on the details he claimed to have done in the interview to the KGB or any other secrets about the Concorde programme.
For one, questions marks remain over why Mr Doyle was never prosecuted – despite admitting spying for Russia.
UK Parliament records seen by the BBC raised that very question on the 18 October 1971.
The Attorney General at the time said he had been consulted about the possibility of a prosecution under the Official Secrets Act, but a prosecution would be unlikely to succeed, based on the evidence, and criminal proceedings should not be started.