I float this as an explanantion ... pure hypothesis you understand.
EAL maybe only has fuel payment credit at a number of places, so maybe has to take on enough fuel for positioning to Southend, return trip to Cardiff, and repositioning to ... Bournemouth was it?Having landed at Southend and then done some weight calcs discover that fuel+full pax+short sector = too heavy to land at Cardiff. Solution .. dump pax. Any other theories?