A PRIMARY school caretaker who embarked on a nationwide letter bombing campaign has been told he will serve at least five years in prison.

Miles Cooper - whose actions injured eight people including a man in Kent - was given an indeterminate jail sentence today after being found guilty of 11 charges.

One device was sent to Michael Wingfield at his home in Folkestone. He suffered cuts to his hands and stomach when it blew up as he opened it.

He sent seven letters, five of which exploded. The DVLA , a forensic science lab and a computer firm were also targeted, in a protest against what Cooper saw as Britain's "authoritarian" government.

The 27-year-old from Cambridge denied eight counts of causing bodily injury by means of an explosive substance, two counts of using an explosive substance with intent to disable, one count of making explosives and one count of possessing an explosive substance.