Team GB's Laura Trott wins women's omnium's gold

Team GB's Laura Trott has won gold in the women's omnium.

Trott was second going into the final event, but she produced a scintillating performance in the time trial to earn her second gold medal of London 2012.

American Sarah Hammer, who headed the omnium after the first five events, was forced to settle for silver while Australian Annette Edmondson earned the bronze.

Trott's triumph has handed Team GB their 21st gold medal of the London Olympic Games.