[mjhall]

The only means I know of for one to reliably detect the image on the screen would be TEMPEST style attacks [1]. I doubt that Capita can afford to buy the necessary equipment, or even views it as economically viable given the volume of letters they sent out - 56 million letters were sent in 2009, for example [2].

I'm not sure if modern TVs will even emit anything obvious since the connection from the decoder to the panel is covered in EMI shielding.

[1] : http://en.wikipedia.org/wiki/Tempest_(codename) [2] : http://www.tvlicensing.co.uk/about/foi-administering-the-tv-...