*:That's being unfair to Horne, who was given access to the Macmillan papers on condition he didn't publish until after Macmillan's death, to avoid any embarrassment to the living. Horne was entirely frank about Boothby's bisexuality and Lady Dorothy's extramarital affair (which was a great source of embarrassment, but hidden from the general public until Horne published his book). Horne alludes to the obscure, much later Eton rumour, but concludes it was 'almost certainly' baseless, while Ball is actually even more critical and adduces a slanderous intent, whose agenda this encyclopedia can't be intended to advance, by repeating it, even as an extremely dubious item of childhood trivia. Cullen's book is a tertiary source written on a different subject; on Macmillan she is dependent on Ball, so her opinion, whatever it may be, must be held as less authoritative than either Ball or Horne, who both discount it.