Hannah Miley secured a World Championship place with a win in the 400m individual medley final at the British Championships in London.
Scotland's Miley, who won the 200m butterfly on Tuesday, finished in four minutes 32.16 seconds, which was 0.85secs inside the qualification mark.
Aimee Willmott was second and Rosie Rudin third.
Jazz Carlin followed up victories in the 400m and 800m freestyle races with success in the 200m event.
Miley has struggled to repeat the kind of form which saw her claim silver at the 2011 World Championships.
However, she showed signs of improvement with an impressive 400m individual medley gold at the Commonwealth Games in Glasgow last summer.
"I feel I'm a different athlete to three years ago and I know how to approach things better," she told BBC Sport. "It's great to see a bit of improvement."
Carlin is well-known for her prowess in distance freestyle events, but surprised 200m pre-race favourite Siobhan-Marie O'Connor on the final night of the British World Championship trials.
The Bath-based swimmer set a Welsh record of one minute 56.88 seconds, to finish ahead of O'Connor and third-placed Eleanor Faulkner.
"It's a bit of a shock to be honest as I know how strong Siobhan is," said Carlin,
"I'm just swimming the 200m to be part of the relay to be honest, so I'll focus on the 400m and 800m at the Worlds."
Thomas Laxton also set a new Welsh record of 52.40 seconds in what was a breakthrough 100m butterfly victory, which should secure him a place in the World relay team.
Braxston Timm (52.72) and Adam Barrett (52.74) filled the other podium positions.
England's former European and Commonwealth champion Elizabeth Simmonds claimed the 100m backstroke title on Thursday and booked her place on the plane to Russia by winning the 200m event in 2:08.38.
Georgia Hohmann was second and Youth Olympic silver medallist Jessica Fullalove third.
England's James Guy claimed his second title of the week with victory in the 400m freestyle (1:46.32), with Robbie Renwick securing silver and Calum Jarvis bronze.
Eight swimmers automatically qualified for the 2015 World Championships in Kazan, Russia, with head coach Bill Furniss due to reveal the full line-up next week.
Automatic British World Championship qualifiers:
Adam Peaty, Hannah Miley, James Guy, Siobhan-Marie O'Connor, Jazz Carlin, Roberto Pavoni, Chris Walker-Hebborn and Elizabeth Simmonds.