Halsall, who clocked 24.47 seconds in the shorter event on Wednesday – well inside the qualifying time for next month's World Championships, touched in 55.20 secs.
Another to impress at Ponds Forge has been Adam Brown, who broke Mark Foster’s British record in the 50m freestyle earlier in the week.
And he is safely through to the semi-finals of the 100m after finishing fastest in 49.15 secs.
In the men’s 200m backstroke heats Craig McNally led the way in 2:00.71 minutes, while Ryan Bennett was satisfied with his performance in qualifying second fastest in 2:01.25.
He said: “That was alright, morning swims are always quite tough. I’ll get back, rest now and hopefully come back quicker.
“I’m hopeful of making the final. I think I will have to go quite a bit faster than that but it should be good. I’m hoping to do well in the final. I feel like I’m in good shape.”
Elsewhere, Michael Rock posted the fastest time in the 100m butterfly heats as he swam 53.22 secs, Molly Renshaw was the quickest qualifier in the women’s 200m breaststroke heats and Adam Peaty set a new personal best of 1:00.75 in advancing to the men’s 100m breaststroke semis.
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- Sports & Recreation