There's an AIBU thread about this too, but I thought I'd collect the relevant info here.
The Secretary of State for Justice, David Lidington, is the only person with the power to overturn the parole board's decision. His web page here has his email address:
www.parliament.uk/biographies/commons/david-lidington/15
It also has a phone no. for his constituency office - they are open until 7.00pm apparently.
Guardian article:
www.theguardian.com/law/2018/jan/04/black-cab-rapist-john-worboys-released-prison
Telegraph article:
www.telegraph.co.uk/news/2018/01/04/taxi-rapist-john-worboys-released-prison/
Please find time to email and see if we can overturn this travesty of justice.