Cavell was arrested not for espionage, as many were led to believe, but for "war treason", despite not being a German national. She may have been recruited by the British Secret Intelligence Service (SIS), and turned away from her espionage duties in order to help Allied soldiers escape, although this is not widely accepted. Rankin cites the published statement of M. R. D. Foot, historian and Second World War British intelligence officer, as to Cavell having been part of SIS or MI6. The former director-general of MI5, Stella Rimington, announced in 2015 that she had unearthed documents in Belgian military archives that confirmed an intelligence gathering aspect to Cavell's network. The BBC Radio 4 programme that presented Rimington's quote, noted Cavell's use of secret codes and, though amateurish, other network members' successful transmission of intelligence.