Russian expert James Nixey told ITV News that he does not think the meeting between Russian President Putin and Prime Minister Cameron will "result in a substantial change in position."
He says there is still a "fundamental divergence of values" on the issue, and he does not think "one pre-judo meeting" will accomplish.
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More than 80 prominent Britons, including Boris Johnson, Russell Brand and former Government ministers, urge Obama to release Aamer.
Thundery overnight with a Met Office warning for rain in place for a large swathe of the country. Quite sunny throughout tomorrow.
Video shot in Islamic State capital Raqq purportedly shows at least two of three missing London schoolgirls.