'Everything was normal that day, apart from how it ended'

Moors caught fire. Fuel tanks exploded.

Debbie Simpson headed for the beach. It was a happy family outing - Mrs Simpson and her two young boys with her sister, Jacqui, and her two children.

But as they picked their way home through the traffic to Darlington, Mrs Simpson's stepmother was being murdered as she sunbathed.

The killing of Ann Heron at Aeolian House is still, nearly 20 years on, notorious for its brutality and because its perpetrator remains unidentified. Yet, as Mrs Simpson agrees, 90 per cent of the public believe they know the identify of the man guilty of what was County Durham's first unsolved murder since 1952. It is Peter Heron, Mrs Simpson's father and Mrs Heron's second husband, who was charged with her murder in 2005.

Now 73 and living with Mrs Simpson near Billingham, close to Stockton, Mr Heron's personal circumstances caused suspicion to fall on him during the early days of the investigation.

When he was eventually arrested 15 years later, the case against him collapsed before it came to trial.

Still, suspicion lingers on a man who is, in the eyes of the law at least, stain-free. It is in an attempt to alter the public perception, and to prompt the police into re-examining the evidence, that Mrs Simpson has spoken publicly for the first time to The Northern Echo about what she believes to be flaws in the investigation.

She has also recalled her memories of the events of that hottest day, which changed her life forever.

"We were coming home from Whitby via Yarm when I suddenly remembered that I hadn't arranged a waitress for the pub that night," remembers Mrs Simpson, who for five years ran The Blacksmiths Arms, in Swainby, North Yorkshire, with her husband, Graham.

"These were the days before mobile phones were so common, so I was going to stop and ring Graham, but Yarm was chocker, so I thought we would call at Aeolian.

"It was approaching ten to six. I was in a hurry, looking at my watch and as we came near I thought shall I or shan't I?'.

"At the last moment, I looked into the back of the car and all the kids were asleep, so I decided to go on to Jacqui's house and use a telephone box.

"As we went past Aeolian, I looked over. I could see that the door was wide open; the sunbed was on the corner and there was just Ann's silver Micra. I remember thinking I know what you've been doing today', because she was a sunworshipper and it had been such a hot day."

Unknown to Mrs Simpson, only a couple of cars behind her on the A67 was her father, Mr Heron, returning home from work. He was the operations director at GE Stiller (Transport) Ltd, in Middleton St George, only a few minutes down the road.

He had worked there for more than 20 years, helping the founder, Peter Stiller, and his son, Paul, build the business from one lorry to nearly 300.

As Mrs Simpson drove on, blissfully unaware, to the Morton Palms roundabout, where the A67 meets the A66 at Morrisons supermarket, her father turned right into Aeolian House. It is a big white house, built in the Thirties and named after the Greek god of the winds. It is secluded, surrounded only by trees and distant traffic, and its sole access is by the 50-yard drive along which Mr Heron drove his white Mercedes.

He would have seen the same things as Mrs Simpson noticed from the road: the car, the sunbed and the open door. As he pulled up, he would have spotted other ordinary details: Ann's half-full glass perhaps; her radio still playing...

"Everything was normal that day, apart from the way it ended," says Mrs Simpson.

"Ann had gone shopping that morning for an 18th birthday present for the party she was going to that night. Dad went home for lunch as he always did, at one; had a cup of soup and a sandwich as he always did and went back to work at two, saying I will see you', and she would have settled down sunbathing.

"She was seen by a friend on a passing bus at about two o'clock and another friend telephoned her a bit later.

"She always fed Heidi, her dog, at five o'clock, but on that day she didn't."

About 50 minutes after Heidi's scheduled feeding time had passed, 53-year-old Mr Heron walked in through the front door.

The police officer who led the case later remembered his first steps through the same front door: the immaculate home, the ticking clocks, the illuminated electric fire, the body lying facedown in a pool of blood in the otherwise perfectly tidy room.

"Dad looked in the main lounge on the left and saw Ann lying on the floor and he remembers saying what the...',"

says Mrs Simpson.

"Then he realised something horrible was wrong. He bent down and touched her and there was blood on his fingertips. He ran to the phone and dialled 999 and then called Paul Stiller. The depot is only a few minutes away and Paul and a colleague got there before the police. Dad was slumped against his car. He asked Paul to go in. Tell me I'm wrong,' he said, but Paul went in and came out and said I'm sorry...'.

"Then the police came."

Mr Heron had grown up in North Ormesby, Middlesbrough, where he had met and married his first wife, Catherine.

They had three children, Mrs Simpson and her twin younger sisters, Jacqui and Beverley, but after more than 20 years, they had grown apart.

In 1984, Mr Heron had gone on a golfing weekend with some friends to the Isle of Bute, off the west coast of Scotland.

There he had met Ann Cockburn, who was nine years his junior. She had been married, with three children, to a police officer for 15 years.

Something sparked.

When Ann, who was originally from Glasgow, came to visit a friend in Darlington, they met up again and the spark grew into a flame. In 1986, both divorces came through and they married outside their Catholic faith, at the Methodist Chapel, in Yarm Road, Darlington.

"Ann and Peter were very, very close, almost to the exclusion of us, his children,"

says Mrs Simpson.

"They wanted to be alone, just the two of them. For somebody so attractive, she was unassuming and shy."

It must have been a happy time. The transport business was thriving. They were comfortably off, settled in an enviable house, Mr Heron working close to home and Ann working part-time as a care assistant at Trees Park, just down the road. Possibly even a dream life.

Until the hottest day of 1990.

Mrs Simpson had picked her way home from the beach, dropped Jacqui and her kids off at their house, stopped at a phone box to arrange a waitress, fought her way back through Yarm to Swainby, at the foot of the North York Moors, where she had dropped her boys - Gary, four, and Andrew, two - at her mother-inlaw's house for their supper and a bath, and she had made it to the Blacksmiths for the dot of seven.

"I did the shift and went back behind the bar," she recalls. "At about a quarter to ten, one of the staff came in and said your sister's here with her husband, she's very upset'.

"It was Jacqui, and the moment I looked at her face I knew it was something major.

"She was crying, walking towards me with her hands out and I was backing away because I knew it was something big and she said Somebody has killed Ann'. Everything after that is a blur."

They dashed to Darlington police station, where Mr Heron had been taken after he discovered the murder.

"He was in total shock," says Mrs Simpson. "The police said he could go home as long as there was a telephone in the house. Jacqui and Martin didn't have a phone at this time, so dad came home with us.

"We got back and I remember changing the sheets on our bed and he just went straight into the bedroom, shut the door and I have never ever heard sobs like it coming from that room.

"Every time I closed my eyes to sleep, I could hear them and all I could see when I drifted off was a man's figure bending over me."

Mrs Simpson knows that if, on the way back from the beach, the traffic hadn't been so busy; if they hadn't been running quite so late; if the four children had not all been peacefully asleep, she would have turned right down Aeolian House's long drive through the trees and, ahead of her father, she would have made the grim discovery.

"On one hand, I'm glad for the sake of the children and for Jacqui that we didn't stop," she says, "but on the other hand, I wish we had because I could have sheltered dad from what was to come."

If you have information about the Ann Heron murder, call Durham Police on 0845-60-60-365. Or call anonymously to Crimestoppers, the independent charity, on 0800-555-111.

Or call Debbie Simpson on 01325-505062, or write to her c/o The Northern Echo, Priestgate, Darlington DL1 1NF