Original sentence: Diana was firstly educated at Silfield School in Kings Lynn, Norfolk, then at Riddlesworth Hall in Norfolk and at West Heath Girls' School (later reorganised as the New School at West Heath, a special school for boys and girls) in Sevenoaks, Kent, where she was regarded as a poor student, having attempted and failed all of her O-levels twice
Edited sentence: Diana was firstly educated at Silfield School in Kings Lynn, Norfolk, then at Riddlesworth Hall in Norfolk and at West Heath Girls' School (later reorganised as the New School at West Heath, a special school for boys and girls) in Sevenoaks, Kent, where she was regarded as a poor student, having attempted and failed all of her O-levels twice - a spectacular achievement in itself