It's not the "British Facebook", it's someone who bought the domain and pointed it towards Google Sites. See http://www.facebook.co.uk/ .

Of course, I was not able to see the Google sites connection, but it makes sense a squatter would snatch the url and direct it to their own site for affiliate monies or something along those lines

Open the www. URL and open the "sign in" link in the site footer.

whois(1) is your friend:

    Domain name:
        facebook.co.uk

    Registrant:
        Technomicom Inc.

    Registrant type:
        Non-UK Corporation

    Registrant's address:
        2 Greenwich Office Park 3rd Floor
        Greenwich
        CT
        06831
        United States

    Registrar:
        Register.com Inc [Tag = REGISTER-DOT-COM]
        URL: http://www.register.com

    Relevant dates:
        Registered on: 30-Dec-2004
        Renewal date:  30-Dec-2012
        Last updated:  08-Feb-2011

    Registration status:
        Registered until renewal date.

    Name servers:
        dns091.b.register.com
        dns209.c.register.com
        dns225.a.register.com
        dns249.d.register.com

    WHOIS lookup made at 23:53:03 12-Feb-2012

http://gawker.com/5071172/facebookcouk-offline--but-check-ou... http://whois.domaintools.com/facebook.co.uk

At least it's not a 503 Bad Gateway...

SCANDAL