The 6ft 1in 21-year-old from Shoreham was second for most of the race but just edged out Russia's Anastasia Zueva in the final metres.

 

 

Spofforth's is the first gold won in the pool by the British team, following the silver and bronze won by Joanne Jackson and Rebecca Adlington in the 400m freestyle.

 

Keri-Anne Payne won the 10km open water swim last week, the day after 15-year-old Tom Daley had become Britain's first-ever world diving champion.

 

But Michael Phelps, who won a record eight Olympic gold medals in Beijing last year, was beaten by Paul Biedermann in the 200m freestyle.

 

It was the 14-time Olympic champion's first defeat over four lengths in serious competition since the Athens Olympics in 2004, when he was beaten by Ian Thorpe and Pieter van den Hoogenband.

 

The German set a new world record of 1min 42.00sec and in the process broke his second iconic record in two days after taking Thorpe's 400m free mark on Sunday.

 

Spofforth's victory means she is Britain's first long-course world champion since 2003 when Katy Sexton - also a Portsmouth Northsea backstroker - and James Gibson claimed gold at the World Championships.

 

She said: "I am really excited with that result."

 

Spofforth, a student at the University of Florida, had already broken the British record twice yesterday, with 58.78 in the morning heats followed by 58.74 in the evening's semi-final.

 

The semi-final time would have been enough to take the world record away from Zimbabwe's Kirsty Coventry, but Zueva had set a new record of 58.48 earlier in the evening.

 

Spofforth said: "I took it out a little bit faster than I went yesterday.

 

"That is when the speed came in, and I came home a little bit faster."

 

Spofforth had finished fourth in the 100m backstroke at the Beijing Olympics last year.

 

She said: “Last year I missed out on a medal by one hundredth of a second and this year I have won the gold by one hundredth of a second.

“I gave it my all but I wasn’t sure whether I would make it and come back at the Zueva but I did it.

 

"I swam a better race than in the semis.

 

"I was very relaxed coming into this final and didn’t feel the tension like I normally do at other major meets.

“I am just delighted.

 

"It means so much to me and I just want to go back and sit on my bed and relive it again.”
 

Team-mate Elizabeth Simmonds finished seventh in 59.71.

 

The 2007 World bronze medallist Liam Tancock swam to a new Commonwealth and British record in the 100m backstroke final.

Tancock had an explosive first 50m and turned in second place as he fought against Japan’s Junya Koga and Germany’s Helge Meeuw through the final length of the pool.

He eventually touched in joint fourth place in a time of 52.73, just 0.10 of a second off the bronze medal.

Tancock said: “I have been working on that for some time now.

 

"That was a best time for me and to get it in the world final was great.

“It was a British and Commonwealth record and it was pretty exciting to be part of a race that saw the Championship record go.

“The backstroke events are moving on and that was a tough field out there tonight and I just missed the medal. It is unfortunate not to win the medal but tonight it just wasn’t my turn.”

The gold went to Koga in 52.26 and Meeuw took the silver in 52.54.

 

The bronze was won by Spain's Aschwin Wildeboer, who touched in 52.64.

 

Japan's Ryosuke Irie touched in 52.73 to finish in joint fourth with Tancock.