Im using the Luton flight this Saturday into Knock and also surprised about an additional flight on a Saturday. A Friday or Sunday fair enough but it must have been a case that they were doing nothing else with the plane!
Maybe this flight is more geared up for a 'gathering' festival Saturday night goer, get into Sligo/Galway/Westport for 5/6 have a night of it and head back to good auld Landon Town the next day.
Well that's my best attempt - already the normal Gatwick, Luton & Stansted flights on a Saturday although this extra flight is a welcome addition.