It might be the only interesting thing ever to come out of the Scotland Office.The memo leaked by former Scottish Secretary Alistair Carmichael through his special adviser in April was dynamite.The notes on a conversation between SNP leader Nicola Sturgeon and French ambassador Sylvie Bermann recorded an admission from the First Minister that she would prefer David Cameron to remain in Downing Street after May’s election. Carmichael, quizzed on Channel 4 News, said it was nowt to do with him, guv’nor.The problem? Ms Sturgeon said it wasn’t true. The French consul general said it wasn’t true. And eventually Carmichael said it wasn’t true, thus bringing to an abrupt end one of the least promising careers in political leaking.