A teenage boy was "moments away" from carrying out a high school massacre after going to class with a shotgun, knife, balaclava and 200 rounds of ammunition, a court has heard.

The "polite, model student" armed himself with the intent of carrying out "a shooting that would have taken a dreadful place in the history of truly wicked crimes" committed in Britain - but had a last minute "change of heart", Warwick Justice Centre was told.

The boy, who cannot be named, took the double-barrelled shotgun and 200 cartridges from his dad's cabinet as well as a knife, balaclava and ear defenders.

He then spent his first lesson with the firearm concealed in his trousers at Higham Lane School, in Nuneaton, Warwickshire before excusing himself from class and going to a side room.

As he was putting on ear protectors in preparation of his massacre he suddenly saw sense and phoned 999.