A man who disrupted this year's University Boat Race by swimming into the path of the rowers is due to be sentenced for causing a public nuisance.
Trenton Oldfield, 36, told the court that he wasprotesting against government elitism.
He's been warned he could face a jail sentence.
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Officers were given the touching letter at Brixton Station while they were on a reassurance patrol after yesterday's attack
The 52-year-old had previous convictions for violence but was not on the anti-terror watchlist.
In a statement Charlton Athletic said: Keith was a true hero who will be greatly missed by all the Charlton family and everyone at the club.