As someone who has just travelled by train from Runcorn to Cardiff and back in a day, i would have welcomed an air link from Liverpool to Cardiff. Yesterday proved a very long day, left Runcorn Station at 07.30 and got back at 22.30. Their were no delays or any problems on the trains it just takes a very long time.
I think Liverpool to Aberdeen should also prove popular as well, this route has operated in the past and was well supported.