Rebecca Adlington has won her second gold medal of the Beijing Games, becoming the most successful British swimmer of the past 100 years.

She finished the 800m freestyle six seconds ahead of Italy's Alessia Filippi in a time of 8:14.10, and 2.12 seconds inside Janet Evans' 19-year-old world record.

Adlington, who won the 400m freestyle earlier in the week, said: "It's so nice when you work so hard and it pays off. I wasn't expecting that. I am so pleased. I knew would be tough and was expecting a battle but when I knew I was clear I felt I could go for the time."

She was a favourite to win the race after setting an Olympic record in the 800m freestyle heats on Friday.

Her two sisters Laura, 21, and 24-year-old Chloe, watched the race on television at their home in Mansfield with other relatives. Her parents Kay, 48, and Stephen, 50, watched from the poolside in Beijing.

After the race Laura and Chloe spoke to their sister on the phone. Laura said: "We knew she had it in her. She started strong and she kept it going all the way through. Everybody in the room was on their feet, screaming and crying. There's no word for the emotion, it was absolute jubilation."

She added: "Her face when she looked up at the board and realised what she had done was just fantastic. When I spoke to her on the phone I didn't know what to say because well done doesn't cover it really.

"She deserves it all. She put so much work in, both her and her coach to get themselves to where they are now.

"It's nice for her now. She can enjoy it as the pressure is off. She has done a lot more than she set out to do so she can relax and watch the rest of the games. We are just looking forward to having her home and celebrating as a family."

Chloe said: "It was an Olympic final so you don't know what's going to happen as it's the biggest sporting competition in the world.

"We knew she would do well if she got a good start but it's fantastic for her to get two golds. When we spoke to her she was just being normal Becky, taking the mickey out of dad and asking how the dogs were.

"We don't know how it will change things when she gets back. She needs to talk to our parents. She will have a holiday and relax and then we will let her do what she wants to do."

Adlington said she now plans to spend time out of the pool with her boyfriend and family.

© Independent Television News Limited 2008. All rights reserved.