World 50m breaststroke champion James Gibson returned to form after a poor Olympics by booking his place in the GB team for the World Championships.
Gibson, who only came sixth after being tipped for a 100m medal in Athens, was first home ahead of Darren Mew in a time of 28.02 secs in Manchester.
Only the winner of each event can qualify, and even then they need to match a certain time.
James Goddard earned his place in the team, matching the British 100m record.
Goddard, so cruelly denied a medal in the 200m in Athens after Aaron Peirsol was disqualified then re-instated, clocked a time of 54.90 secs, equalling the mark set last year by Gregor Tait.
Mark Foster failed to achieve the qualification mark in the 50m butterfly
despite touching first in 24.72 secs, while the same fate befell Christopher
Cozens in the 100m freestyle.
Kirsty Balfour was in record-breaking form as she booked her place in Montreal with victory in the 100m breaststroke in a Scottish record time of one minute 08.66 secs.
Kate Haywood came home second, and was left counting the cost of having met the qualifying standard for Montreal in the semi-final, as only times clocked in the final counted towards qualification.
Rebecca Cooke broke her own British record in the 400m individual medley, in a time of four minutes 46.54 secs, but it was almost five seconds outside the qualifying time for Montreal.
Elsewhere, Terri Dunning also missed out on a trip to Canada despite winning the 100m butterfly, and 14-year-old Francesca Halsall, who is going to the European Junior Championships in Budapest, won the 50m freestyle.
The main news of the day was double Commonwealth gold medallist Sarah Price announcing her retirement after finishing second in the 100m backstroke.
Fellow seasoned campaigner Karen Pickering failed to make the 200m freestyle final, and world 200m backstroke champion Katy Sexton withdrew from the 50m event after coming fourth in the 100m.