AS three teenage killers last night began their four-year jail sentences, the father of their victim called for a change in the law where murder can be reduced to the lesser charge of culpable homicide.

The three, Ross Gravestock, Graham Purves, and Iain Wheldon - all from middle class families in the affluent Edinburgh suburb of Balerno - were originally charged with murdering Mark Ayton but during the course of the trial pleas to culpable homicide were accepted by the Crown.

Mark's father, tax inspector Malcolm Ayton, said although he understood the reasons for the Crown's decision, the system which allowed this was flawed. It also resulted in sentences which were too lenient and offered no deterrent to others.

''There is a lot that suggests to me that these are very lucky young men and the law has worked in their favour,'' he said. ''I think an appropriate sentence is one that gets the mix of punishment and deterrence right.

''Anything less than 10 years would send out the wrong message to other people who may want to carry on in the same way. I think we need to look at the law. Murder has an emotive ring to it which is perhaps not useful.''

The Aytons are still trying to come to terms with their loss.

''Mark was not a sullen, angry teenager. He was a bright, caring, happy go-lucky 19-year-old. A very cheery young man,'' his father said. ''It has torn our lives apart. We are still very, very upset.

''We have resolved to try to get back to as much normality as we can in the circumstances, but our lives are never going to be the same. Birthdays, Christmas and new year are normally happy times. They are now going to be very poignant for us for the rest of our lives.''

Mark Ayton, an apprentice diesel mechanic, was kicked and punched to death as he and his brother Paul were walking back to their home in Cherry Tree Loan after a night out playing pool and drinking at the Kestrel pub in Balerno.

They were initially involved in a scuffle near Balerno High School, which began with anti-English taunts. This led to a chase and a second attack on Mark whose body was found behind a garden wall.

Mr Ayton said: ''We have worked very hard to reassure Paul that in the circumstances his actions on the night were absolutely textbook. He could not have done anything more to help his brother.''

The family have been touched by the messages of sympathy from friends and strangers alike in a peaceful suburb still stunned by such a violent outrage. ''We have no intention of moving from Balerno, and until this incident we have been very happy here. People in both Currie and Balerno have been extremely supportive and helpful,'' Mr Ayton said.

He added: ''It is very worrying that people from such good homes can kill other people the way they did here. It is the barbarity of it all. It was a pretty brutal way to go. It just seems that Mark was in the wrong place at the wrong time.''

Mr Ayton 46, said Scotland should move to a more sensible system of people being charged with homicide, allowing the courts to decide a sentence which reflected the seriousness of the offence.

He said the forensic pathology evidence which prompted the plea to a lesser charge was irrelevant to the crime which had left his son with 18 wounds to the head.

''Whether he choked on his own blood or vomit whilst unconscious or whether brain damage was the cause of death - that to me is a matter of detail.

''Witnesses in court told of hearing shouts of 'Kill the f---ing bastards' - and one of them was holding a bottle at the side of the street. When there are 18 blows to the head, it should be murder. This wasn't a 'square go' that went wrong,'' Mr Ayton declared.

He dismisses claims that bad feeling between pupils at Balerno and Currie secondary schools lay behind the killing. Instead, he gives far more weight to anti-English taunts which led to the initial scuffle.

He was born in Glasgow and his wife Jean is from Johnstone in Renfrewshire. Although Mark was born in Scotland, the family lived in London, Birmingham, and Telford before moving back to Scotland six years ago.

''Both my lads have been teased before about their accents. It was all small beer and did not cause any great offence,'' he said. ''But the anti-English jibe seems to have been the start of it.

''Scots people as a race believe themselves to be open and friendly to visitors and incomers. I think we should all wait a little and examine if this is borne out by the evidence. It appears that anti-English taunting is not taken seriously.

''It is certainly something I never experienced as a Scot when I lived in England. I sincerely hope it is not something that is endemic in Scotland.''

However, only the killers know the real motivation and Mr Ayton remains very bitter towards them, particularly as the four-year sentences could see them back on the streets of Balerno within 18 months, given remission and time spent on remand.

Mr Ayton said: ''I do not want to hear, or see or have any time for them whatsoever. I have slightly different concern for the parents who will be pretty shocked at what's happened.

''It must be difficult to come to terms with the fact that their sons are killers. I have some sympathy for them but their sons are still alive and mine is dead.''

Meanwhile, the notion that time heals all wounds remains a platitude in the Ayton household: ''I do not believe the anger and bitterness will subside. I think we will feel exactly the same way but we will think about it less often over the years to follow.''