The 30-year-old took eight seconds off his existing landmark when he clocked 18 minutes 20.97 seconds, with Tom Partington second in 22:17.26.

Bosworth, who was seventh in the 20km at last year's World Championships, said: "I'm the happiest and healthiest I've ever been."

Meanwhile, Beth Partridge took the high jump gold, with Morgan Lake second.

Partridge cleared 1.87m with her first attempt as Lake could only make 1.84m, meaning 2019's standings were reversed.

"I don't really have any words to sum up how awful that was," said Lake, who had three failures at 1.87m, having won with 1.94m last year.

In the women's 20km race walk, Abigail Jennings, 19, won with a personal best of 25:28.46, ahead of Pagen Spooner.

Elsewhere, Amelia Strickler took a step up from last year's silver to win the shot put gold with a 17.97m mark in round four, ahead of defending champion Sophie McKinna's 17.39m.

Naomi Ogbeta retained her triple jump title courtesy of a 13.83m leap in round two.

Liverpool's James Williams produced a personal best of 47.24 seconds to take the men's 400m ahead of Joe Brier (47.92) and Krishawn Aiken (48.00).

The women's race was won by Jessie Knight - who is still combining her training with her work as a teacher - in 52.76, with Holly Turner second in 54.22.

Adam Hague won the pole vault with 5.55m, 40cm ahead of runner-up Ethan Walsh.

Melissa Courtney, who was second behind Laura Muir in last year's women's 3,000m, took advantage of her absence this time to win in 9:48.54.

Guy Learmonth also improved on his silver last year to secure the 800m with a personal best of 1:46.89. Ama Pipi's personal best of 23.23 sealed the women's 200m, and Andrew Morgan-Harrison took the men's 200m in 21.20.

Michael Puplampu retained the men's triple jump with a leap of 16.21m, while the high jump went to Tom Gale with 2.27m, with defending champion Chris Baker coming third.

Keely Hodgkinson edged out Mari Smith by 0.35 of a second to win the 800m in 2:04.37, while the final event, the men's 1,500m, was won by George Mills in 3:50.69.