Worthy of note:
IT Security Expert published an excellent article Why UK Privacy is Dead on the dangers of identity theft and the lack of privacy in the UK, whose risks are unintentionally heightened by such lists as the online electoral register. He includes links and telephone numbers for getting oneself removed from the lists of direct mail advertisers aka unsolicited junk mail and similar phone calls. Both take requests for removal online or by phone.
http://www.192.com/, one must apparently download a form and mail it in. The page where the form download link is located reveals that credit checking firms conducting credit checks can access the register and check your details even if you have opted out.
While unwanted mail and phone calls are annoying and time wasting, the criminal use of personal details to effect fraud through social engineering is far more damaging when it happens. The Electoral list, BT Phone Book and online job search websites can all be leveraged by fraudsters. One must consider the benefits and the risks of providing one's data or allowing it to remain public. Unfortunately, as IT security Expert notes, the default is that an individual's data is published and available unless it suits the commercial or organizational interest of the body that has collected the data.