In the case of the Tilgate playground the police and council managed to get something, which is probably not illegal, removed from a website within a day or two of learning about it.
In the case of Redwatch, the police and Home Office say they can do nothing because the site is hosted in the US, despite the contents provoking racial intolerance, inciting violence, etc. etc. They will not even act against one of the mirror sites, containing the same illegal material on a UK server.
But lets remember the Internet is just a medium. I don’t blame the Internet for Redwatch any more than I blame it for specific videos on YouTube. Any blame rests squarely with insecure racist morons.