Foreign Secretary William Hague said he hopes today's summit on sexual violence in war will be a "turning point" in the battle against war zone rape.
He responded to US Secretary of State John Kerry on Twittter:
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The Labour leader did not say whether he would maintain Britain's nuclear deterrent programme.
Ukip leader Paul Nuttall also said he would want to get rid of Sharia courts.
Over 40,000 people picked up their packs to take part in the annual marathon in the capital.