The social networking site Twitter has introduced a new way to report abusive messages after several London women were victims of trolling.
The online company came under fire after journalist Caroline Criado Perez received violent and threatening 'tweets'.
Lucrezia Millarini reports:
More top news
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.