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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Ms Ardern posted a photo showing her and Clarke Gayford with the baby at Auckland City Hospital.
Nasa says scientists have found 95% of near-Earth objects measuring a kilometre or bigger, but the remaining 5% could inflict big damage.
There will be showers during the morning across Scotland, but these will clear during the afternoon.