The piper had not finished his lament yesterday when the dragon's roar of London's traffic drowned out the unofficial Cenotaph service for those shot at dawn.

Eight decades on from the end of the First World War, the 306 British soldiers shot for desertion are still dishonoured, still shamed, still the subject of the official disapproval of Her Majesty's Government.

The microphone at the Cenotaph had been turned off, and the traffic kept at bay for only a brief moment by the police. The homage of Labour MP Andrew MacKinlay - 'We shall remember them' - was all but sabotaged as a silver Saab revved up and the exhaust of a souped-up superbike echoed across Whitehall.

We shall not remember them. We shall not remember Herbert Morrison, who was the youngest soldier in the West India Regiment when he was led in front of the firing squad and gunned down for desertion. A 'coward' at just 17.

We shall not remember the moment when Gertrude Farr went to the local post office in 1916 and was told: 'We don't give pensions to the widows of cowards.' She was left destitute, with a three-year-old and a four-month-old to feed.

We shall not remember the poor soldier who confessed: 'I haven't been the same since I scraped my best friend's brains from my face.' He, too, was shot at dawn.

To this day, the Ministry of Defence refuses to give a pardon to the 306, convicted of cowardice, though even in 1914 people knew all about 'shell shock' - what the modern world calls Post Traumatic Stress Disorder.

The daughter of Harry and Gertrude Farr was at the Cenotaph yesterday to hear the piper. Still fit and spry at 86 years, Gertrude Harris told of the agony of her father. He went over the top countless times from the day he joined up with the British Expeditionary Force in 1914. He was shelled repeatedly, collapsed with the shakes in May 1915 and was sent to hospital. 'He shook all the time. He couldn't stand the noise of the guns. We got a letter from him, but it was in a stranger's handwriting. He could write perfectly well, but couldn't hold the pen because his hand was shaking.'

It is possible that Farr was suffering from hypacusis, when the ear drums are so damaged that the auditory nerve is exposed and the victim cannot physically bear loud noises. This is a condition familiar to people in Northern Ireland caught up in bomb explosions. Whatever his precise ailment, Farr was sent back to the front line.

He struggled on for months, and went through the Somme unscathed. But then something snapped within him. He was in a ration party, moving towards the front line, and he couldn't go on. He went to a dressing station and asked to see a medical orderly. He was told that he couldn't see an MO because he wasn't wounded. The sergeant-major was quoted in Farr's court martial papers saying: 'If you don't go up to the fucking front, I'm going to fucking blow your brains out.' Farr replied: 'I just can't go on.'

The court martial lasted 20 minutes. Farr defended himself. The decent doctor who had first got him to hospital had been injured and could not defend him. General Sir John Haig - one of the donkeys who led the lions - signed his death warrant. Farr was shot at dawn on 16 October 1916.

And that is not the worst. There was no war pension, only shame. Gertrude said yesterday: 'I only knew the truth about what happened to my father when I was 40. My mother never, ever spoke about it. She was destitute, and we both went into service.'

The agony did not end with the executions. John Laister died two months ago at the age of 101. All his life he was tortured by the moment he was dragooned into a firing squad. He raised his rifle and, on the command, opened fire. The victim was a boy soldier who had been arrested for cowardice. Laister told BBC's Omnibus, to be broadcast tonight: 'There were tears in his eyes and tears in mine. I don't know what they told the parents.'

The historic shaming of men - and, consequentially, their women and children - happened in other countries too. In France and Germany men were shot for cowardice and desertion. But in the case of Germany, only 25, not 306. And in both countries that shame was lifted within a decade of the end of the war when official memorials were built.

Only in Britain do we continue to dishonour the victims of shell shock. The Government's argument echoes the one first set out by John Major. He told the Commons that pardoning the 'deserters' would be an insult to those who died honourably on the battlefield and that everyone was tried fairly.

Documents released under the 75-year-rule give the lie to the last point. Soldiers accused of cowardice were not given fair trials; they were often not properly defended. The evidence against them was often contradictory. Tom Stones's great uncle, Sgt Will Stones of the Durham Light Infantry, was shot for desertion, but any reading of the case papers shows that no court today would have convicted him. Instead, he would probably have got a medal. He blocked the trench with a rifle, which had been sheathed on the orders of Major Bernard Montgomery. For this he was convicted of 'shamefully casting away his weapon in the face of the enemy'.

Thus far the Government has resisted appeals to give a Millennium Pardon for those shot at dawn. Mackinlay told The Observer yesterday: 'It appears there are still some Bufton Tuftons in the Ministry of Defence who resist this. None of the relatives want compensation, only justice and the return of the good name of their loved ones.'

Some of the executed were clearly under age. The Ministry of Defence defended this last barbarity in a letter dated 24 March 1999 to Shot At Dawn campaigner John Hipkin from MoD historian A. J. Ward. She wrote: 'You also state that a number of soldiers who were under-age were illegally tried and executed. This is not the case. Anyone over the age of 14 was deemed legally responsible for his actions and Army regulations provided no immunity from Military Law for an under-age soldier.'

That may have washed in 1918. For the Government to continue that defence of bureaucratic inertia in 1999 is as plain a disgrace as the silent microphone.