Nearly every speed camera in Britain could be declared unlawful as a result of a concerted legal challenge to the entire programme.
It appears that back in the grey days of the early 90's before Tony and his band of merry muppets came along and "saved" us all, the home office may have made a bit of a lash-up over the 1991 road traffic act. All cameras in use at the time were given a blanket approval, but the argument goes that the consent could only apply to technology in use at the time, and not the mess of new cameras that we now have milking the motorists across the country. Thus the new cameras couldn't have consent under the terms of the 91 act, and are therefore illegal.
However since most of the judiciary are more than happy to toady to the government in the hope of an honour or 2, I really can't see this one succeeding due to the complex house of cards that it would upset. But it's nice to have hope once in a while.