Respects have been paid at a ceremony for Armistice Day at the Cenotaph in Whitehall.
Wreaths were laid at the foot of the monument, following a two-minute silence to remember Britain's war dead.
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Accompanied by the Duke of Edinburgh, the Queen will attend the opening ceremony of the fifth session in the Holyrood chamber.
Ms Leadsom has received the backing of Ian Duncan Smith, the former work and pensions secretary.
The former shadow work and pensions secretary is considered a more viable candidate than Angela Eagle, a Labour source has told ITV News.