Rebecca Adlington and Jo Jackson took inspiration from Federica Pellegrini's stunning 400 metres freestyle victory at the World Championships in Rome.

The pair claimed Great Britain's first medals in the pool at the Foro Italico on Sunday as Pellegrini became the first woman to swim under the four-minute barrier, finishing in three minutes 59.15 seconds.

The British pair both set new personal bests, Jackson touching second in 4mins 00.60secs with Adlington - swimming from lane eight after a poor heat swim - third in 4:00.79.

Pellegrini became the first woman to go under four minutes 36 years after it was achieved by a man and 53 years after Lorraine Crapp became the first woman to break the five-minute barrier.

The atmosphere had been red-hot before the race and the Italian's victory was greeted with deafening roars and a rousing rendition of the national anthem.

Pellegrini got her tactics all wrong at the Olympics in Beijing last year having gone into the event as favourite, with Adlington taking gold and Jackson bronze, but it was a different story on Sunday.

Adlington said: "It's very different this time and obviously on home ground she has got all that crowd cheering for her, it's definitely her night.

"It's definitely something I'm going to remember for the rest of my life. And in London (2012) that will be our crowd.

"We just want to better what she has done."

Adlington was the only swimmer to wear a Speedo LZR among a sea of more modern Jakeds and Adidas suits.

She joked: "I've proven that you can still get a medal."

The FINA Congress have voted to return to textile suits after the furore surrounding the performance-enhancing suits containing polyurethane.

A further ruling also means bodysuits will ultimately be a thing of the past, with the new rules set to come into effect on January 1, 2010.

Adlington continued: "Me and Jo are both so glad that we have gone back to the knee suits.

"We are both so excited about it."

When asked if she thought wearing one of the newer-generation suits would enable her to have gone faster, Adlington said: "Maybe I could have gone a bit faster but at the end of the day I wanted to compare my time with last year and I wanted to be able to come next year and know that I can hopefully go just as quick in a knee suit."

Jackson was proud to have been a part of history, adding: "I tried to stay with her (Pellegrini).

"When she went I was just kicking so hard but she swum an amazing time to break the four-minute barrier, it's an amazing thing for her to do - and to be part of that race.

"I'm just glad to have come away with a medal."

Elsewhere, David Davies was eighth in the final of the men's 400m freestyle and the men's and women's 4x100m freestyle relay squads were both seventh as six world records fell in the Eternal City.

Today sees triple world medallist Liam Tancock go in the 100m backstroke, with Gemma Spofforth and Lizzie Simmonds in the women's race.

The finals session features Hannah Miley in the 200m individual medley, the Scot third fastest in a new British record in the semis.