Olivia Forsyth, says Craig Williamson, will be remembered like Le Carré's little drummer girl: used, abused, chewed up by the espionage system and left as incidental detritus on the side of the political road, writes Jonathan Ancer in his new book, Betrayal, published by Tafelberg.

At the heart of the saga is this question: when Forsyth made contact with the ANC in exile, did she do so as an infiltrator or a genuine defector? When Forsyth confessed to Garth Strachan in Zimbabwe, he didn't believe this was a genuine homecoming to the ANC but just another ploy to infiltrate the organisation. He believes that she wanted to play a triple agent game: she was pretending to come over to the side of the ANC but was still planning to work for the South African government and the security police.

"Can I prove that? No," he says. "My assessment is based on the five or six times I met with her. I think she was an extremely troubled individual. She told me about her affair with Oosthuizen at Rhodes and said she suffered meltdowns and he would come to Grahamstown to put things back on track. My feeling is she had...