Kirsty Wark’s diary: On the Caledonian sleeper, the new Donna Tartt, and a week of Edinburgh shows

There isn’t a Scottish politician in living memory who hasn’t been on the Caledonian Sleeper. I always imagined Donald Dewar folding himself up in his berth, he was so tall. He was notoriously sniffy about the company he kept in the bar and once recounted the horror he felt when — stuck in snow — he was forced to fraternise with practically the rest of the Labour front bench for 22 hours somewhere south of Carlisle. Journalists tend to be more comradely. The other night, I took the sleeper in tow with an old family friend, the BBC reporter Allan Little. Over Glenfiddich and cheese we exchanged scurrilous gossip and book recommendations before, just north of Watford, he made his long way back to the Edinburgh end of the train. On less sensible nights, say with Martha Kearney, I have stayed up long after my bedtime — perhaps even as far as Preston.