Conservative MP Andrew Rosindell, secretary of the All-Party Parliamentary Group on the Falkland Islands has told ITV News that the Islanders "have a right a right to make their own decision" and that Argentina should not interfere.
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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.