If you make a habit of using these, invest in a couple of these:
http://www.ebay.co.uk/itm/LAPTOP-IN...Accessories_PowerSupplies&hash=item56517616f1
There is a very good chance this will not work - the specs do not mention the sensitivity of the device, so its possible it will only arrest surges from the likes of lightning strikes and such. It will also do nothing to protect your equipment from "dirty" power, or sags.
Either way, DO NOT use these sockets. They are clearly not for public use, either lacking a sign advising that you may use them, or having a label of some kind saying otherwise. Not to mention the fact that many of them are not in areas where you would expect to find a plug socket for passenger use.
Regardless - you are plugging your equipment into a socket located in private premises without permission. Would you go into ASDA and use one of their plugs? Or how about when you're waiting at the Post Office... The list goes on, and for this reason plus more I'd say legally the chances of a TOC being held responsible for damage are minimal.
My job often requires me to use such sockets (they're not just used for cleaning equipment), and if people keep using them, then we will likely see T-Key locked covers or Walsall fittings put in place. This will drive costs for the railway up, and make the lives of some staff pointlessly difficult.
Jon