Smile
Except maybe that you arrived in NCL in the middle of the day and I arrive early morning and return the same day, where as you have to overnight to catch the return flight as the aircraft is doing something else on its return to Cardiff maybe some remote French village, where it goes tech and you have your flight cancelled because it is a low cost carrier and you have paid for no frills.
Eastern will find another aircraft or possibly reroute the Southampton into Cardiff first. I rest my case while you have your champagne in the Newcastle Travel Inn or GNER buffet car