DIANE OSBORNE’S husband died in her arms. ‘After I’d called the ambulance, I begged Bob not to leave me,’ she says.

‘I kept saying, ‘Baby, don’t leave me. Don’t leave me now. Please don’t leave me.’ But he went purple, stopped breathing and died.’

Afterwards she went into deep shock. ‘I had terrible shakes and couldn’t even hold a cup without the liquid pouring out. I’ve been crying a lot and haven’t felt like going from day to day.

‘Each morning I wake up and remember that Bob is dead and I feel sick. I used to eat a lot, now I hardly touch a thing unless somebody forces me. I’ve had terrible nightmares, always the same dream in which Bob is dying and going blue.

‘At first when people spoke to me, the words didn’t even go through my ears to my brain. I couldn’t remember a thing for six weeks – I had to write everything down.

‘Even now I can’t recall things properly. But I can remember everything that happened that night most vividly.’

Robert Osborne, a husband and father of three, was fatally stabbed just before Christmas last year. He was 40 years old.

He was killed by Joseph Elliott, a drugged teenager whom Robert had followed with a hammer when he caught him slashing neighbours’ car tyres for fun. Yesterday an Old Bailey jury allowed the 19-year-old killer to walk free. Diane, 38, is sitting in the kitchen of their rented family home in Streatham being comforted by her sister-in-law Patricia, who lives next door. Diane wears jeans, looks wan, smokes roll-ups and drinks Liebfraumilch. ‘I’m devastated. Justice stinks,’ she says furiously. ‘Elliott admitted taking drugs, slashing tyres and stabbing my husband. But they still said he wasn’t guilty. My husband is now dead and his killer is free.’

She appears alternately distraught and numb. Nothing prepared her for the jury’s verdict. ‘I expected murder or at least manslaughter for that boy,’ she says, looking dazed. (She rarely refers to Elliott by name, generally calling him ‘that boy’.) ‘I don’t have feelings of revenge. But I want a retrial. I’m told I can’t get one because I don’t have any more evidence.’

Elliott’s miserable childhood was used as an excuse in court. ‘But my dad died of cancer when I was 15,’ says Diane. ‘I almost died when I was 12, my mother suffered from mental illness and I was brought up in three foster homes.’

She looks sadly at her two labrador-cross dogs and cat playing nearby. ‘It’s unreal to say that someone doesn’t turn out right because of their childhood.’

She recalls the events of 10 December last year when she was in her garden watching an eclipse of the moon. Robert, a musician and music tutor, was inside decorating.

‘I heard a hissing noise and went out and saw these two guys slashing tyres then trying to break into a pensioner’s house.’

She followed them but fled when they faced her and went back to ring the police. Robert said she shouldn’t bother. ‘We’d called them out before and they hadn’t come. They’re too busy. My car had been done twice before and so had Bob’s. His handbuilt car was his pride and joy.’

Robert grabbed a hammer. ‘He’d had enough of this sort of vandalism. He just wanted to demand an explanation and get their names. He would never ever have used the hammer. He picked the hammer up by its head and just took it for protection.’

He followed the unemployed youth (who was high on LSD, drink and cannabis) to a local council estate, cornered him on a balcony – and was stabbed through the heart.

Diane had followed her husband: ‘Bob ran downstairs to protect me. He collapsed. I tried to stop him kicking Bob while he was dying,’ she says heavily. (In court, Elliott denied kicking his victim as he lay dying.) ‘He punched me around the head and rib cage.’

She holds back tears as she remembers her husband. They’d been together 16 years but she’s shocked and says she cannot remember when they married.’

‘Everybody says they’ve never seen a closer couple. Now it’s been taken away.

‘He was a good father and husband and a just, quiet man. He’s the most gentle man in the world. He used to take spiders out of the bath and put them in the garden to avoid hurting them.

‘He lived for his music and family. He was very clever –and used to teach 13 to 17-year-olds. He also played guitar in pubs with a band or on his own.

‘Our house was derelict when we moved in four years ago – and he did everything from the plumbing to building a pond in the garden. He was so happy that wildlife was thriving in it.’

Diane has coped with life by ‘living for the trial, thinking it would bring justice’.

‘She kept saying her life was over when he was killed,’ explains Patricia. ‘But she kept going so she could see his killer brought to justice.’

How did Diane feel when she saw Elliott? ‘It was very hard. I kept remembering him as I saw him on the night – mad, out of his head, vicious and dangerous.’ After the verdict, Elliott whooped with delight and Diane broke down in tears.

She returned to her ‘broken family’. She has three children – Tarina, 19, Justin, 18, and Lisa, 14. (Yesterday Tarina was on holiday in Spain.) The effect on the children has been devastating. ‘Lisa has done nothing but cry her eyes out. When I told her her father was dead, she went mad.’ They also face the prospect of meeting Elliott because his council flat is 300 yards from Diane’s home. He lives in squalor on an estate littered with cars with missing wheels, syringes on the ground and graffiti. ‘If I bump into him, I don’t know what I’ll do,’ she says, quietly. ‘I suppose I’ll have to do what I did in court and walk by, bite my tongue and hide my tears.

‘I will not move from here,’ she adds, forcefully. ‘It’s my house and Bob did the decorating. If I move somewhere else where there’s no decorating by Bob, my life will be as empty as my heart is now.’

She is also terrified that Lisa will bump into Elliott on her way to school. (Lisa had, in fact, met Elliott before the tragedy. ‘He spoke to me,’ she says. ‘He’s dirty and he always looks like a tramp. I saw inside his home and it’s disgusting.’) The Osborne family is united in their horror at Elliott’s acquittal. ‘When the jury foreman stood up and read out the verdict, I thought another juror was going to stand up and say it was a joke,’ says Justin, a former store security guard.

‘It was bad enough having to go through his death and the funeral, but this really might just finish us off.’

Later, next door, Robert’s brother Mark, a builder, said: ‘How can a peaceful bloke like Robert go out of his house to protect my car, get beaten to death and his killer go free? Those 12 people who let that bastard out should be examining their consciences today.’

Previously Diane had faith in the system of justice. ‘But if I walked into the Queen’s house or didn’t pay my poll tax I’d be locked up tomorrow,’ she says now.

‘We live in a society where people are allowed to slash old ladies’ throats while they’re in bed and rape little girls and get away with it. Now you can’t even go out and protect your car without ending up dead. If that boy had robbed a bank he would have got time.’

Diane’s future is bleak. ‘I’m now trying to survive on income support. I’ve lost his teacher’s salary and have to get by on £70 a week. I’ll scrape through financially. But emotionally I don’t know what I’ll do. I’m knackered. I haven’t got any strength left and nobody can help me.’ She looks down. ‘My husband paid with his life for having a hammer. He died for nothing.’

Self-defence or not? How the judge guided the jury FOR LEGAL reasons, the judge, the prosecutor and the jury in the Robert Osborne murder trial are unable to defend themselves against the mounting tide of public concern.

But, by examining transcripts of the case, it is possible today to throw more light on the way it was handled.

This is an edited version of Mr Justice Kay’s direction to the jury: ‘The only lawful justification for this killing that arises is the question of self-defence.

‘Self-defence is lawful when it is necessary to use force to resist or defend yourself against an attack or threatened attack, and when the amount of force used is reasonable.

‘I emphasise two words: necessary and reasonable.

‘There are, thus, three matters that you have to consider. First and foremost, was the defendant acting in self-defence at all.

‘The defendant tells you he wanted no part in any fighting and if he is or may be right, then clearly his actions were entirely to defend himself. ‘If, however, you accept the evidence of Mr Osborne’s widow, for example, that the defendant shouted down a challenge to Mr Osborne, the prosecution say there is no question of him simply acting in self-defence. ‘Secondly, there is the question whether it was necessary to resort to the use of the knife at all. The defendant says that he was not intending to stab, merely to wave the knife in front of him and that it was Mr Osborne whose momentum carried him on to the knife. Thus he asserts that he was doing no more than was necessary.

‘Thirdly, was the defendant using no more force than was reasonably necessary? What is reasonable depends on all the facts, for example, the nature of the attack or anticipated attack, whether or not a weapon is used and whether or not the attacker was on his own.