Katherine Grainger wins Olympics rowing gold at fourth attempt

Great Britain won its fourth Olympic gold in 24 hours - and sixth in total - as Katherine Grainger and Anna Watkins triumphed in the women's double sculls.
Grainger, 36, was a silver medallist at three previous Games, with the world champions clocking six minutes 55.82 seconds.
"I never had a doubt. With 750m there was only going to be one winner. That is the story of the British medals so far at these Games."
Britain have further opportunities at gold, with the men's team pursuit cycling at 18:12 BST, Victoria Pendleton in the keirin at 18:38 and Rebecca Adlington defending her 800m freestyle title at 19:45.
Australia took the silver and Poland the bronze.
The gold came twenty minutes after the men's pair of George Nash and Will Satch won bronze.
Earlier in the morning, Jessica Ennis broke the British record for the 100m hurdles in the opening event of the heptathlon.
Victory brought GB's second rowing success following Heather Stanning and Helen Glover's win in the women's pair on Wednesday.
Watkins and Grainger are now unbeaten in 23 races.
Since they teamed up in 2010, the duo have claimed two World Championship titles, bringing Grainger's total to six world gold medals overall.
The pair were the form crew coming to the Olympic regatta at Eton Dorney, comfortably winning gold in all three World Cups.
Grainger said: "It was worth the wait. Steve Redgrave promised me there would be tears of joy this time and they are. For both of us we knew we had the goods to perform and it was about delivering."
Watkins added: "I can't believe it. I've tried to keep my mind away from this moment. It was just another race but it was the right one."