The motorcyclist is said to be aged in his early 20s and was wearing light grey tracksuit bottoms with a double light blue stripe down each leg, a black jacket and black gloves which had plastic caps on the knuckles. He was also wearing a green and silver crash helmet.
The bike he was riding is described as a black and green off-road machine with Evo-Tech written on the front shocks.
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Saturday evening's weather update for the west
A man from Eastbourne who was stabbed by the Westminster attacked has told ITV Meridian he should have been jailed in 2003.