A Worcester teenager who mounted a campaign of terror and aggression against his elderly grandparents has been sent to detention for three-and-a-half years.

Christopher Field was said by Recorder Mrs Darbyshire to have made life a misery for Marjorie and Terence Jones, both 72, and he was being locked up to give them respite from his activities.

Field, aged 18, of Mayfield Road, Rainbow Hill, pleaded guilty at Worcester Crown Court to blackmail and three charges of harassing his grandparents and sister by putting them in fear of violence.

Ian Ball, prosecuting, said Field came from a troubled background and had lived with his grandparents until they were unable to cope and he went to a foster home.

In July 2000 he went back to live with his mother but continually returned to his grandparents to demand money.

He was particularly abusive to his grandmother, who had had eight strokes, was partially-sighted and used a wheelchair.

She was vulnerable and intimidated, said Mr Ball. If Field's demands were refused, he would fly into a rage, punching holes in three doors, smashing windows and the telephone.

He also made calls costing hundreds of pounds on their telephone and was violent towards his 16-year-old sister.

Miss Michelle Heeley, defending, said Field had been corrupted during his time at a foster home and had been distressed at the age of 13 when his father died.

He had tried to hang himself and taken out his anger and frustration on his grandparents.

He had repaired relationships with his mother and felt that he was entitled to money which had been left in trust for him.

The recorder said the interview with the grandmother was one of the saddest documents she had ever read.

Mrs Jones was clearly petrified and Field had reduced her to tears on numerous occasions.

Many children had disrupted lives but they didn't terrorise their families in the way in which Field had done.