Jo Jackson smashes 400m freestyle world record

BRITAIN'S Jo Jackson smashed the 400m freestyle world record - and claimed the scalp of Olympic champion Rebecca Adlington.

RECORD BREAKER: Jo Jackson reversed Beijing form to beat Rebecca Adlington and break the world 400m freestyle record

Jackson - who won the bronze behind Adlington in Beijing - touched home in 4.00.66 at the British Gas national championships in Sheffield.

Adlington claimed silver in 4.00.89, a time quicker than her gold medal winning swim last summer, and Jazmin Carmin took bronze.

Italy's Federica Pellegrini held the previous world record - 4.01.53 set at last year's European Championships in Eindhoven.

“I'm completely blown away by the world record and at last I have beaten Becky at the finish,” said Jackson, who now qualifies for this summer’s Fina World Championship in Rome.

“I knew I had been swimming well. I had been going good in training but you never know how you are going to do until a final.

“I have never even had a British record in the 400m so to get the British and then the world record is amazing.

“Becky also ducked under the world time and that is something to shout about as well.”

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I CAN'T BELIEVE IT: Jo Jackson, congratulated by Rebecca Adlington, admitted even she was shocked by her world record time in Sheffield (Getty Images)

Jackson – who now trains at Lougborough University - credits a change in environment as a major factor in reversing Beijing form.

“I have been doing so many different things in training it - I have been swimming alongside David Davies and Caitlin McClatchey and that has really helped,” she added.

“Maybe Rebecca's dominance has assisted me as well because I know I have to beat an Olympic gold medallist just to win a national title now.

“It is so tough to beat her whenever she is competing - she is always in good shape.”

RYAN BANGS in Sheffield