Team GB athletes such as Commonwealth 200m breaststroke champion James Wilby, Olympic breaststroker Molly Renshaw and World Championships individual medley swimmer Abbie Wood were among a top-quality field hoping to achieve qualification times for the Tokyo Olympic trials at the Corby long course.
For the Boston club, Rico Bringeman and Oscar Goldsmith left with gold medals.
Rico won the 14 years 200m butterfly.
He was also tipped for gold in the 800m freestyle, being the fastest seed, but on this occasion he had to settle for silver.
Rico also claimed a second-place finish in the 1,500m freestyle and bronze in the 400m freestyle.
Oscar won gold in the 11 years 200m butterfly, and event in which teammate Bradley Holland took bronze.
He also won silvers in the 400m individual medley and 400m freestyle, plus bronzes in the 100m freestyle, 200m freestyle and 50m breaststroke.
In the 12 years events, Stefano Fiore took the bronze in the 200m butterfly an Alfie Bisby was third in the 400m freestyle.
Every Boston swimmer swam a long course PB, with many swims even beating their short course PBs.