The 19-year-old from Liverpool turned in third place at the 50m mark behind Australia's Libby Trickett and Germany's Britta Steffen.

 

Steffen, who held the world record going into the final, was in second place behind Trickett at the turn but it was Halsall that had the best finish.

The British record holder stormed through the final 50m as she overtook Trickett, a three-time Olympic gold medallist, to win the silver medal in a new British record time of 52.87sec.

Halsall said: “I can’t believe it.

 

"I was dreaming of a medal but to win silver in such a fast time is amazing.

“I just saw Britta’s wave and thought if I am on that I’ll be there or there abouts.

 

"I turned to myself and said it is your last individual event and I just gave it all my heart.

 

"My arms were failing but I just wouldn’t give in.

“This is just the most amazing moment for me, I am ecstatic.

 

"I am only 19 years old and I hope my best years are ahead of me but it is looking good for London [2012] off the back of that swim.

“The whole spirit on this British team is amazing, it is infectious and you are seeing the results of that.”

Steffen won the gold medal in a world record time of 52.07 and Trickett took bronze behind Halsall in 52.93.

 

She joins the British roll of honour which already includes gold medallists Kerri-Anne Payne and Gemma Spofforth, silver medallist Jo Jackson and bronze medallist Rebecca Adlington.

 

The women's 4x200m freestyle team also won a bronze medal.

 

There should be more British medals to celebrate tomorrow after Adlington and Jackson's (pictured) efforts in the pool this morning have given rise to real optimism the pair may once again share a podium after they were fastest into tomorrow's 800m freestyle final.

 

Olympic champion and world record holder Adlington dominated her heat from start to finish to qualify fastest in 8min 20.53sec.

 

Jackson was even more dominant in her heat, with a winning margin of 15 metres, finishing in 8:20.80, meaning the British pair will occupy lanes four and five at the Foro Italico tomorrow evening.

 

The pair had finished second and third in the 400m freestyle earlier in the Championships.

 

Their performances were even more impressive considering just 16 hours had elapsed since they formed half the squad that came third in the 4x200m freestyle relay.

 

The threat to their hopes of claiming two of the three medals on offer for the second time this week comes from Beijing silver and bronze medallists Alessia Filippi and Lotte Friis and Camelia Potec, fourth last year.

 

Adlington said having her fellow Briton Jackson as company in the final as "brilliant" but she refused to identify any one swimmer as a potential threat.

 

She said: "Everyone in the pool.

 

"It is a clean slate, it is anybody's.

 

"The strong ones are through.

 

"All the contenders are there."

 

The 20-year-old from Mansfield knows there is more expectation than last year.

 

She said: "A little bit.

 

"People are aware of me now whereas last year I wasn't really known."

 

The semi-finals of the 200m Backstroke saw Elizabeth Simmonds break the British record after touching in a new personal best time of 2:07.21.

Simmonds took the race out from the start and knew she had to get a quick time under belt in order to make the final.

She led throughout the race and touched home in first place in her semi-final after knocking over a second off her personal best.

 

She qualified as the third fastest athlete for the final.

Simmonds said: “I had a disappointing swim this morning but that certainly made up for it.

 

“I got my head in gear this afternoon and just went for it.

“I went out fast and was desperately trying to hold on but I didn’t think it was going to be that fast.”

Spofforth qualified for the final after finishing in second place behind Simmonds in a time of 2:07.64.

 

She goes into the final ranked in fifth place.

Spofforth said: “To have Lizzie alongside you before the race takes all the nerves away and I am so happy we both made it through tonight.

 

"We both had two impressive swims and it will be good to be there in the final.”