A teenage gang killed a mother in a prank by pushing a lit firework through her letterbox after a string of bullying attacks on her son, a court heard yesterday.

Mary Fox, 59, died in the fire in Bodmin, Cornwall on Bonfire Night last year after the Silver Dart was thrust inside to "frighten" the family, a jury was told.

Her son Raum, then 17, escaped through a window of the blazing council home in Wallace Road, but his mother inhaled a fatal amount of fumes. Owen Hewitt and Ryan Croft, both 18, and a 17-year-old who cannot be named, later "laughed and joked" that the burning house belonged to Raum's mother, Truro Crown Court heard.

Opening the case to the jury prosecutor Paul Dunkels QC said: "On November 5 last year, three young men were wandering around Bodmin with a large quantity of fireworks.

"They took a rocket, snapped the stick off it, lit it and put it through the letter box of the home of Mary Fox and her son Raum at 51 Wallace Road.

"It set fire to the house. Raum was able to escape by jumping out of the first floor window. Mary Fox could not get out. She was overcome by fumes and smoke from the fire, and died."

The group did not intend such dire consequences but only wanted to "give the occupants a fright," Mr Dunkels added.

Mr Hewitt, of Bodmin Foyer, Kestenenn and the younger defendant have pleaded not guilty to the manslaughter of Mrs Fox, and also denied a charge of arson being reckless as to whether the life of Raum was endangered.

Mr Croft, of Wallace Road, had earlier admitted both allegations, the jury heard.

Raum had been bullied at school because of his acne and alternative dress sense, Mr Dunkels claimed. When Mrs Fox escorted him to school that just made the problem worse, he added.

He said: "Raum Fox, 17 at the time, used to be bullied at school. He had bad acne on his face, and used to dress differently to other children.