THE daughters of a frail elderly couple killed in their own home said today: "We still don't know why our parents had to die."

York-born Catherine Wilkins and Anne Squires thanked York residents who rallied to comfort them as their world turned upside down after the deaths of James and Joan Britton.

They said the flood of sympathy cards from friends and family had been "wonderful" and had helped them cope with their pain.

Mrs Wilkins, 48, said today: "There have been so many, even from people we do not know or had lost contact with.

"The support has been amazing. We've been overwhelmed by it - it has been wonderful."

Speaking exclusively to their "local" newspaper in a direct thank-you to York, the sisters told how the shocking deaths of their parents were something they could not have imagined "in their wildest dreams".

The nurses hailed the "round-the-clock" dedication of police officers seeking chief suspect Mark Hobson and of garage owner Derrick North, who helped find him.

Mrs Squires said she wanted to shake Mr North's hand, and said he was a hero. "He was very calm and cool."

The sisters also praised police support they received, and their parents' "fantastic" neighbours in Strensall Road, Strensall.

They also revealed how they supported each other after the killings that shocked the nation.

"We've not had time to fall apart," admitted Mrs Wilkins, who said their careers had given them some insight into the loss. "We've had our moments, but we've got to take it day by day."

The grieving sisters hit out at the "cowardly" crime, telling how their kind-hearted parents could have been "knocked over with a feather".

Mrs Wilkins, speaking from her Durham home, recalled the devastating Sunday night police arrived at her door with the tragic news.

"My first reaction was one of disbelief," she said. "First of all the police said there had been an incident.

"Given their age I assumed that something might have happened to one of my parents, but never in my wildest dreams did I imagine something like this could have happened. They never feared for their safety."

James, 80, and Joan, 82, were found stabbed to death.

On the same day, the bodies of sisters Claire and Diane Sanderson were discovered in a flat at Camblesforth, near Selby.

Police later said they wanted to question Claire's boyfriend, 34-year-old Mark Hobson.

"We still do not know why it happened," said Mrs Squires, 53, who lives in South Africa. "As far as we can tell it seems completely random." Her parents had been burgled by "opportunists" before, but felt safe.

The sisters grew up in Fulford and Clifton. They still have strong York links with many relatives in the city.

Mrs Wilkins said she still saw York as home.

The mothers-of-two paid tribute to their parents, who moved to their Strensall house in 1976.

They recalled how their father used to sell honey from his gate.

Their mother, who worked as a school secretary, was a "homemaker" and loved gardening.

Updated: 10:33 Wednesday, July 28, 2004