Everybody helped organise the trip but Callum worked harder/the hardest of all

Callum worked the hardest of all in helping to organize the trip. His dedication and determination were unmatched, and he went above and beyond to ensure that everything ran smoothly. From coordinating transportation and accommodations to managing schedules and activities, Callum's efforts were invaluable. He consistently put in extra hours and showed a level of commitment that was truly impressive. Without a doubt, Callum's hard work was instrumental in the success of the trip.