Abstract: A mobile telephone or tablet or the like (40) for viewing commercial television programmes has a display screen (41), a firewall (70), and behind the firewall a first, sealed data storage section (42) which stores personal attributes of a viewer, such as a child, supplied on a token (32) from a trusted third party (10), a second, unsealed data storage section (44) to which the personal attributes are copied, the second section having a flag (48) which is set when the data in the second section has been modified by the viewer, and a third data storage section (46) in which personal preferences can be stored by the viewer. Adverts from advertisers (50) targeted on the data in the second and third sections are sent to the device (40), headers in the adverts are checked against the data in the first section, and adverts are rejected if they are unsuitable for the viewer.

Abstract: A mobile telephone or tablet or the like (40) for viewing commercial television programmes has a display screen (41), a firewall (70), and behind the firewall a first, sealed data storage section (42) which stores personal attributes of a viewer, such as a child, supplied on a token (32) from a trusted third party (10), a second, unsealed data storage section (44) to which the personal attributes are copied, the second section having a flag (48) which is set when the data in the second section has been modified by the viewer, and a third data storage section (46) in which personal preferences can be stored by the viewer. Adverts from advertisers (50) targeted on the data in the second and third sections are sent to the device (40), headers in the adverts are checked against the data in the first section, and adverts are rejected if they are unsuitable for the viewer.