The paratrooper was convicted of murdering an 18-year- old girl, one of two teenagers shot dead by troops while in a stolen car in west Belfast in 1990. The verdict has produced an outcry from some of Britain's most senior military figures: had he been acquitted, there would have been an outcry from Irish nationalists.
The Irish view is that someone has been held accountable for killing two teenagers whose offence of travelling in a stolen car did not warrant the death penalty. Large sections of middle England, by contrast, view Pte Clegg's life sentence as an undeservedly harsh fate for a soldier doing a difficult job in dangerous circumstances.
One of the reasons for the gulf in perception is political: many people in Britain are inclined to support their army and disinclined to regard criticism of it as anything other than republican propaganda. Another is attention to detail: much of middle England takes scant notice of media or other reports of the record of the soldiers.
Many Irish nationalists, by contrast, subject the army's record to the most exacting critical scrutiny, and almost automatically think the worst of it. Thus the clash of cultures: the man in Essex filters out the bad bits, while the man in west Belfast revels in sinister suspicions and conspiracy theories.
Many of the 300 people killed by the army over the 25 years of troubles have been armed terrorists, about whom few tears are shed. But many, too, have been civilians, including children, who have been killed in a variety of controversial ways.
Most of these controversies have failed to attract the attention of middle England, but in Ireland, both north and south, many have come under microscopic examination.
The authorities can point to the fact that there have been more than 30 prosecutions of members of the security forces involved in killings. The critics respond that Pte Clegg is only the second soldier convicted of murder, and that the first, Pte Ian Thain, was quietly released from prison and allowed to re-join the army.
The critics cite this record as evidence that the legal system has been designed to ensure that security force prosecutions are rare and convictions even rarer. In other words, the charge is that after dubious incidents, the authorities are more concerned with protecting army personnel than with serving justice.
The case of Pte Clegg is one of many in which the original army version of events has been overturned and exposed as untruthful during subsequent court proceedings. In this case, in fact, it is almost certain that there would have been no prosecution hadit not been for evidence given by an RUC officer.
The original trial involved six soldiers, including an officer. The judge in the no-jury proceedings heard that on 30 September 1990, Pte Clegg was one of 16 paratroopers accompanying an RUC officer on an anti-joyriding exercise in west Belfast. They were in an area plagued by joyriders.
The soldiers divided into teams, some setting up a checkpoint but discontinuing it after a stolen car drove through without stopping. As they were walking along a dark road another car appeared, and rifle fire directed at it.
The soldiers said they opened fire because the car was threatening the lives of colleagues. All testified that the vehicle had struck one of the defendants, Pte Barry Aindow, on the leg. A large number of shots were fired, one of them killing the driver,17-year-old Martin Peake. Two more shots fatally injured a backseat passenger, 18-year-old Karen Reilly.
The court heard that the RUC officer originally corroborated the soldiers' story, but later went to his superiors and made an 11-page statement in which he said that no one in the patrol was in any danger from the car, and that Pte Aindow had not been struck.
He further testified that the soldiers, apparently realising the circumstances of the shooting would get them into trouble, had deliberately caused an injury to Pte Aindow's leg to create evidence that he had been hit by the car. One soldier had been chosen by the others - he heard a paratrooper being told, "Get down, you're it," and when he lay on the ground another soldier stamped on his leg.
A traveller who lived in a nearby caravan gave evidence of seeing a soldier strike, or appear to strike, a colleague on the ground.
In his testimony, Pte Clegg said he saw Pte Aindow being knocked off balance, and had then fired four shots, three of them at the windscreen of the car as it was coming towards him, and one at the wing as it passed him. He denied firing at the rear of the car and denied firing the round that killed Miss Reilly, although the court heard forensic evidence that one of the shots which hit her came from his rifle and passed through the rear of the vehicle.
He said that after firing the four shots he applied the safety-catch to his rifle and saw Pte Aindow standing in a firing position, having also shot at the car. He could not explain how Pte Aindow, having been knocked off balance as he claimed, could have taken aim and fired in such a short time.
Prosecuting counsel declared: "A soldier is in no different a position than that of any civilian, and where he discharges a firearm, where he intends to kill or seriously injure, and death results, then he is guilty of murder unless it can be justified.
"Had it not been for the RUC constable on patrol with them, and a civilian witness, and the forensic and pathological findings which triggered off the investigations, the means that these soldiers employed might have achieved their objective in covering their tracks."
The judge, in accepting the evidence of the RUC officer, said the shooting had not been premeditated and that Pte Clegg had been presented with a situation not of his own making. He ruled that the first three shots had been legally fired, but that the fourth was fired at the back of the car at a time when it posed no threat and thus made him guilty of murder.
Some considering the facts of the case will conclude that Pte Clegg was guilty of murder; some that he was not guilty and should have been acquitted; some, perhaps, that an intermediate offence should be available so that judges can give out sentences less severe than life imprisonment.
The problem for ministers is that for a quarter of a century they have been arguing in Northern Ireland that murder is murder and that the law is the law, and that a cardinal principle of the British legal system is that soldiers are subject to the same laws as the public.
On many occasions there have been controversial verdicts and sentences involving civilians, but always ministers remained implacably resistant to the notion that the system was making mistakes.
Now they may be on the point of making a special exception in the case of Pte Clegg. The exercise of leniency and mercy for the paratrooper may now win the approval of middle England, but it will provide a stark contrast with the system's treatment of civilians. As far as nationalist Ireland is concerned, however, it would be taken as finally confirming the argument that there is one law for British soldiers and another for everyone else.