The 21-year-old joined Great Britain compatriot Rebecca Adlington on the medal podium, who claimed the first gold for British women's swimming since 1960.

She beat American Katy Hoff into second place.

The British pair reached 100m and 200m in sixth and eighth place respectively.

At the halfway stage, just over half a second separated the field with Adlington reaching 300m in fifth and Jackson in fourth.

American Hoff was half a length ahead with 10m to go, but Adlington stormed up the final 50m to become the British woman to claim gold since Anita Lonsbrough won the 200m breaststroke in 1960.

Adlington and Jackson are also the first British women to win medals at the Olympics since Sarah Hardcastle's silver (400m freestyle) and bronze (800m freestyle) in Los Angeles in 1984.

Jackson's third place in a time of 4:03.52s means the British team have surpassed their entire swimming medal haul from Athens 2004 in one race.

Jo will now join her GB colleagues in the 4x200m relay heats on Wednesday, their sights set on a medal in the final on Thursday.

Jackson had her first taste of Olympic competition four years ago in Athens.

"This time I know what to expect and I can enjoy myself a bit more," she said before competition began.

"I've been to major meets every year since Athens and I've improved every year so hopefully I can improve again this year.

"I'll go to Beijing with my mind open and just see what I can achieve."

The Derwentside club member, who is coached by Dave McNulty at Loughborough University, secured a silver double in the 2006 Commonwealth Games and broke the British record in the 400m and 800m free.

Joanne is the youngster sister of 2001 World Championship gold medal winner Nicola, who swam at the 2000 Sydney Olympics and retired from the sport in 2005.

The GB swim team prepared for the event with a training camp in Osaka, Japan.

Meanwhile, on the water, Masham rower Carla Ashford will compete in the Women's Eights at the Shunyi Olympic Rowing-Canoeing Park.

Her Olympic path begins with tomorrow's heats before a scheduled repechage on Tuesday, and the final on Sunday August 17.

The 29-year-old physiotherapist learned to row during her time at Oxford Brookes University, and the former Masham Church of England School pupil and Cundall Manor School Head Girl raced in the eight in the 2008 World Cup series.

She finished fifth, sixth and third and won a bronze medal in the eight at the World Championships in 2007.

Ashford was a world championships finalist in 2005 and a B finalist in 2006, both in the women's eight.

She raced in the eight in the 2007 World Cup series, always reaching the A Final and finishing second, fifth and fourth.

In 2002 Ashford won the Remenham Cup for women's eights at Henley Royal Regatta and in the same year raced at the World University Championships in the four, finishing fourth.

Carla was a member of the women's sweep squad throughout 2005 having won the squad trials.

She won bronze in the pair at the Lucerne World Cup in July and was a member of the eight that competed at the Versailles International Match and the eight that performed so well at the World Championships in Japan, finishing fifth.

In the 2006 World Cup, she finished sixth in Munich, and then took a bronze in Poznan.

The eight went on to finish eighth at the 2006 World Championships at Eton.

Carla joins Harrogate-born Debbie Flood in the GB rowing team, the 28-year-old Olympic women's quad scull silver medallist who lived in Guiseley before moving south for university.

Flood now lives in Henley on Thames.