Both of my postings yesterday were done from the train. I was on my way to talk at a meeting of the North British Semigroups and Applications Network; a journey of roughly two hours from London.
I travelled up on East Coast Trains. They proudly announced “Free wi-fi”, but it turned out to be 15 minutes free and then you pay, unless you were rich enough to be travelling first class, in which case you could probably afford to pay for your wi-fi anyway. So the post on Apollonian circle packings was done under great time pressure. (The wi-fi is so slow compared to my desktop connection that a job that normally takes a couple of minutes was only just finished before the shutters came down. This is no doubt why a couple of misprints crept in.)
I came home on Grand Central. No passenger information about wi-fi, but I tried it, just in case; there it was, and it was free for the whole journey. So the post about the Higman–Sims graph was done in much more leisurely fashion. (Though I have to admit, the free wi-fi tempted me away from working on the journey!)
The other wonderful thing about Grand Central (whose trains I hadn’t been on before) is something important to me: nice wide seats, and plenty of legroom!
By contrast, Virgin Trains, who run the west coast service, give nothing away free; the wi-fi is provided by a mobile phone company, and you have to register with them before you can start using it (and paying). Once I was desperate enough to try, but didn’t succeed in getting through the registration process.