Welsh swimmers Jazz Carlin and Ieuan Lloyd have sealed places in their final trial as both bid to secure individual Olympic places at London 2012.

Carlin failed in her her 400m freestyle bid in March's trials before pulling out from the 800m because of illness.

The British Championships is her last chance in the 200m but Carlin needs a time of one minute 58.33 seconds in Tuesday's final for a qualifying shot.

Lloyd wants Team GB's second Olympic 400m freestyle spot from his final.

But fellow Welshman Alfie Howes is the fastest qualifier for Tuesday's final in Sheffield as the Cardiff swimmer recorded a time of 3:55.32.

Lloyd, who has already secured a place in Team GB's 4x200m Olympic freestyle relay team, won his heat in 3:57.81 minutes.

But the teenager must hit the Team GB Olympic qualifying time of 3:48.92 at Ponds Forge to join Robbie Renwick in the 400m team at London 2012.

Long-distance specialist David Davies, the double Olympic medalist, is the third Welshman in Tuesday's 400m freestyle final.

Carlin, meanwhile, was eighth fastest qualifier for Tuesday's 200m freestyle final in a time of 2:02.50.

But the Commonwealth Games 200m silver medalist must lower her personal best of 1:59.89, achieved in 2008, by more than a second in the 10-woman final if the Swansea-based swimmer is to join Rebecca Turner in the 200m Olympic team.

And Carlin, a world and European relay bronze medalist, must swim quicker than 1.59.47 to have a chance of Olympic qualification in the 4x200m.

Welsh record holder Georgia Davies, who has already qualified for the Olympics, cruised through her 100m backstroke heat in 62 seconds.

Davies also finished second to fellow Welshman Thomas Haffield in the second heat of the men's 200m butterfly to qualify for the 10-man final.

If Carling does qualify, she will join fellow Welsh swimmers Georgia Davies Jemma Lowe , David Davies and Lloyd in the British Swimming team for London 2012.