Grand Central operate train services from London Kings Cross to: York (non stop) then on to Thirsk, Northallerton, Eaglescliffe, Hartlepool and Sunderland.
Between 24th November and 13th December they are offering 1/2 price fares, in Standard and First classes. You can print tickets at home or store them as a text message.
London to York is non stop and starts from £14.75, and three trains operate each way daily.
Valid on Grand Central Trains services only. Timetables here:http://www.grandcentralrail.co.uk/timetable.html