re-posted, by request:
tabouleh, when you register a domain you are supposed to fill in your details. So mumsnet says:
www.networksolutions.com/whois-search/mumsnet.com
Registrant:
Mumsnet Ltd
Unit 6
Deane House Studios
Greenwood Place
London, England NW5 1LB
GB
Which is fine, mumsnet is a registered company, and that's its registered address, also a matter of record wck2.companieshouse.gov.uk/6e46125629d70b41813a9dd63f633091/compdetails
Slight catch is that whois changes are archived, so if you look at
whois.domaintools.com/mumsnet.com
which is a much better whois service
it says 'Whois History:260 records have been archived since 2003-11-26 . '
so you can subscribe to their whois history for $10/month and look those up. It might happen that in 2003 a personal address was used, but again that's probably not an issue as company directors' home addresses are on Companies House anyway, and it is obviously a business, rather than a blog of someone about their family as with the OP.
Anyway, private domain registration costs £5/year, www.123-reg.co.uk/domain-names/whois-privacy.shtml (other similar services are available), and would prevent casual snooping, although whois history would still reveal the original whois record, so while anyone doing a simple whois on the domain would see 'anonymous', you could still look up the original details, for $10.