Clive Chamberlain from Dorset Police Federation is among those taking part in the march. Officers from every police force in the country are taking part in the protest in London.
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15-year-old Charlotte was killed on a beach in India in 2008. Two men are on trial but her mother says she's unsure justice will be done.
Visitors hoping to see the Man Engine tomorrow in Truro are being warned to get there early amid concerns of travel problems in the city.
Savannah Nicholls has cerebral palsy and severe epilepsy after complications from a bone marrow transplant.