She will fly on Friday from Krasnoyarsk in Siberia to the start of the 636-mile trek at Cape Arktichevsky.

BBC: NEWS | UK | England | Devon | Mum set to start polar ski trek

Her arrival has been delayed by up to an hour due to bad weather, and she will fly into Belfast, before being taken by helicopter to Enniskillen.

BBC: Queen to begin two-day Northern Ireland visit

She is due to fly back to the UK to take part in the London Marathon on Sunday, where she will run in her "Boston finishers" shirt in memory of those affected by the explosions.

BBC: Glasgow & West Scotland

She says she will not go head-to-head with the shinkansen (though her airline will fly between Tokyo and Osaka).

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