It looks like only 4 of the 8 306 boards are marked with an 'X'. Unless it's going to be a joint running with Blyth depot maybe for the 306 / 308?

If staying every 15 mins each, it looks like the new depot will run 4 boards with Blyth running the other 14. If going down to every 20 mins each (which I doubt given the way GNE are heading), it would be Blyth running 10 boards (as they do now for the 308) with the new depot running the other 4.