Last year the 20-year-old University of St Mark and St John student won a British title and two Commonwealth Games gold medals in Glasgow.
He moved city this weekend, competing at the Edinburgh International Meet, but he was again triumphant.
Having won the tough 50m freestyle skins event on Saturday evening, Proud claimed a freestyle double by winning the 100m race on Sunday.
Proud finished in a time of 49.68 seconds to edge out British 200m record holder Robbie Renwick (50.01) and former Plymouth Leander swimmer Calum Jarvis (50.39).
The city swimmer’s main focus now will be next month’s British Championships, which will act as trials for the World Championships in Kazan.