Labour's shadow cabinet office minister has written to the country's top civil servant asking "a number of important questions" over the arrest of the Prime Minister's former deputy policy adviser over allegations linked to child abuse images.
Following claims of a Downing Street cover-up, Jon Ashworth said there were legitimate concerns "given that Mr [Patrick] Rock had a senior role at the heart of Government."
He asked the Cabinet Secretary Sir Jeremy Heywood for information surrounding Number 10's decision to report Mr Rock to police, including when David Cameron was first made aware of the claims.
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Counting will begin on Saturday morning, with the result expected later in the day.
There have been a number of incidents involving heavy goods vehicles getting stuck and causing disruption in recent months.