Police visited Hindley – then being held in HM Prison Cookham Wood in Kent – a few days after she received the letter, and although she refused to admit any involvement in the killings, she agreed to help by looking at photographs and maps to try to identify spots she had visited with Brady. She showed particular interest in photos of the area around Hollin Brown Knoll and Shiny Brook, but said that it was impossible to be sure of the locations without visiting the moor. Home Secretary Douglas Hurd agreed with DCS Topping that a visit would be worth risking despite security problems presented by threats against Hindley. Writing in 1989, Topping said that he felt "quite cynical" about Hindley's motivation in helping the police. Although Winnie Johnson's letter may have played a part, he believed that Hindley, knowing of Brady's "precarious" mental state, was concerned he might co-operate with the police and reap any available public-approval benefit.