Almost unnoticed, a white Toyota appeared from nowhere at high speed and ploughed into them, killing both the boys. The tragedy signalled the start of an eight-year battle for justice which the Isherwoods have had to fight alone.
In the latest shocking twist to their story, the Greek courts are asking the couple to contribute pounds 2,000 towards prison meals for those responsible for their children's deaths. The Government has not been able to help.
Last night, the Foreign Office said it had drawn up new guidelines for the relatives of Britons who die overseas. The guidance follows a succession of complaints from grieving families about lack of official support.
A spokesman for the FO said: "Quite often, people assume that we are able to do more than we can. Relatives tend to think `I am a tax-payer, therefore HMG can pay to repatriate my relative's body.
"HMG cannot do that. We do not have a budget to do so. But we can put people in touch with professional undertakers who can carry out that service."
News of the guidelines follows the distressing case of the Cunningham family who were informed by the FO that their son, Paul, had died in Malaysia of a drugs overdose.
Doreen Cunningham, 49, began making arrangements for the funeral of her son, who was 25, after being told that he had died after swallowing 43 condoms packed with heroin. In fact, the dead body belonged to a drugs smuggler who was carrying a stolen passport which the young British graduate only reported missing 10 days after he was thought to have died.
Mrs Cunningham said: "At the time, I could never imagine he was involved in drugs. It was the worst thing a mother could ever imagine. I must have phoned the Foreign Office a dozen times to check there hadn't been a mistake."
The Cunninghams' experience did not surprise Brian Simpson, Labour's MEP for Cheshire East, who has campaigned for the Isherwoods.
He said: "I just don't believe that our Foreign Office helps British citizens who are abroad and in trouble as much as [do] other EU member states."
Among those who are angry at their treatment by the FO is Simon Regan, whose half-brother, Angus Wilson, publisher of the satirical magazine, Spiked, died in a car crash in Northern Cyprus in September.
Mr Regan said the family had expected the FO to fly Mr Wilson's body back for burial. He was shocked when they were asked for pounds 2,500 to cover the cost. He was even more horrified when the body arrived.
"Poor Angus had been sent back in a cheeseboard box which had been tacked up loosely," he said. "The tacks had come undone and the body had been partly exposed. On top of this rough crate, someone had tacked on a piece of metal which resembled a cross."
British undertakers asked the family for an extra pounds 500 to pay for a proper coffin. Outraged, Mr Regan complained to the FO. "It does appear that Her Britannic Majesty's Consul doesn't give much of a damn about Her Britannic Majesty's subjects once they become corpses."
Tracie Miles, whose brother, Paul, and his girlfriend, Joanna Stickland, were murdered while back-packing in Uttar Pradesh in India, is also bitter. Four years after the deaths, the families have not been able to retrieve the couple's possessions. "It was a nightmare," said Ms Miles. "The whole thing is just appalling. I am bitter and I am angry. The Foreign Office say they will keep you up-dated but they don't. They are really not interested. The new FO guidelines at least let people know where they stand. As well as telling them that a British consulate can advise on the cost of a local burial, and offering to help transfer money from friends or relatives, they also warn that British officials cannot investigate possible crimes or contribute to burial expenses.
The advice has come too late for Joan Isherwood, but she is a never-say- die battler. "It was quite horrendous. We were in a tragic situation: our only two children were killed and I myself was at death's door.
"To then return to your native land and find that there is very little support is like a kick below the belt."