MI5 is compared specifically with the FBI's counterintelligence function rather than with the whole bureau. Clarke uses that distinction to criticize a broad equivalence between the organizations. His example also concerns an official historian whose openly declared connection to MI5 should not be mistaken for a newly discovered secret affiliation.
Notable Point · 16:42-17:31
Why MI5 is not a direct equivalent of the FBI
The comparison separates counterintelligence from the FBI's wider remit and distinguishes an official historian's public role from a covert connection.