In the novel Nemesis, Sir Andrew McNeil is the governor of Manstone Prison. He was present at the meeting chaired by the Home Secretary towards the end of the book where Miss Marple summed up the case and described how she had uncovered what happened to Verity Hunt. This meeting eventually led to a free pardon being given to Michael Rafiel. Presumably Manstone Prison was where Michael Rafiel had been held.
After the meeting and hearing the methodical and relentless manner in which Miss Marple had identified and trapped the true killer, Sir Andrew remarked: "That old lady gives me the creeps."