Welsh Commonwealth champion Alys Thomas looks set to make her Olympic debut at age 30 after winning the 200m butterfly title at the British Tokyo 2020 trials.
The two-time European medallist finished in two minutes 8.09 seconds, which was inside the consideration time for the Games.
“It shows you’ve got to keep going,” said the clearly emotional swimmer.
“The last few years have been really hard and at times overwhelming, so to get the time means the world to me.”
Duncan Scott secured his second title of the event with victory in the 100m freestyle.
The Scot, who was pre-selected for Tokyo 2020 based on his performances at the 2019 World Championships, equalled his own British record of 47.87 seconds following his success in the 200m individual medley final on Wednesday.
“It’s great to equal my personal best,” said the double Olympic silver medallist, who is likely to be joined in Japan by second-placed teenager Matt Richards.
“I thought I could go a little quicker but I’m delighted for the other boys because it’s great to see them coming through really quick.”
England’s 2018 Commonwealth champion James Wilby won the duel with Scotland’s 2014 Commonwealth gold medallist Ross Murdoch in the 200m breaststroke final.
Wilby, like Scott, Adam Peaty and Luke Greenbank, was pre-selected for the Olympics and is likely to line up with Murdoch after both swam inside the consideration time.
“Being pre-selected was a nice safety net but it didn’t take away from the fact I wanted to come here and put in fast swims and set myself up for the Olympic Games,” said Wilby, who was second in the 100m event on Wednesday.
European short course champion Max Litchfield, who was fourth at Rio 2016, looks set to reach his second Games after winning the 400m individual medley.
He finished in four minutes 13.47 seconds and is likely to be joined in Japan by Brodie Williams who was second and also inside the consideration time.
English Commonwealth silver medallist Holly Hibbott won the 400m freestyle final, but her time of 4:07.03 was just over a second outside the consideration time.
Swimmers will have further chances to gain places at the Tokyo Games via the European Championships in Budapest next month and the Mare Nostrum series in early June.