So, on August 26, Noam wrote to his son. "That letter," he said wryly this week, "has gone a long way. But eventually, I hope, it will reach Gilad."
Because Noam's mother was born in France, he - and likewise his children - hold dual Israeli and French citizenship. So when he sat at his home in the Western Galilee to write to Gilad, he made the letter's first addressee the French president, Nicolas Sarkozy. Sarkozy passed it to Syrian president Bashar Assad, who, Noam hopes, will give the letter to the Hamas group holding his son.
Noam Shalit, on even a casual acquaintance, appears to be the last person in the world to be writing to presidents. The family - Noam, his wife Aviva, and their other two children, Gilad's older brother Yoel, 24, and sister Hadas, 17 - is deeply private, and every word he has to say to an outsider is clearly torn from him unwillingly. Except, of course, that he will do almost anything to try to get his son back home.
Born in Nahariya but brought up from the age of two in Mitzpe Hilla, a small community near the Lebanon border, Gilad appears to have been a very ordinary schoolboy. He was, says his father, "good at science and maths", and enjoyed playing basketball with his friends in the neighbourhood. What he liked most of all, says Noam, was collecting statistics about sports. "He liked to watch sports on TV, particularly world championships," says Noam, and his geeky sports schtick seems to have made his friends and family laugh. Any match, anywhere - if you wanted to know the score, you asked Gilad.
Was his son planning a university career after the army? "He didn't mention university," says Noam. "He didn't get a chance to plan anything. He just graduated from high school and then went into the army, straight after his final exams. He's not much of a talker: I don't think he planned anything after the army. He was just going to do his army service and then he would see."
Yoel Shalit had finished his own army service in 2004 and Gilad chose to go into a similar combat tank unit to his brother. His friends and family describe him as "highly motivated" and determined to serve. "It wasn't so easy for him to deal with the training," says Noam. "Sometimes it's difficult for the young people, sometimes it's easy. For Gilad it wasn't so easy; but he stuck with it." After basic training he was sent to guard the security of the settlements near the Gaza Strip. Like every soldier, Gilad got time off. His last leave was three days in the middle of the week. "He left us on Thursday and he was abducted in the early hours of the Sunday after that," says Noam.
"We were at work when the army sent officers to tell us. You never hear anything on the media before the family has been informed so we didn't know there had been an attack. They just told us that there had been an attack on his tank unit and that Gilad had been taken to the Gaza Strip. Afterwards, more information started to come in.
"It was a shock, no doubt. I can't really describe how we felt. But I had experienced this kind of thing already, many years ago. The army came to tell us that my brother" - in fact, Noam's twin - "had been killed in action in the Yom Kippur War".
So there was a grim familiarity about the army visit - except that this time, there was no definite news about his fate. In all the months since June 2006, no-one has been able to tell the Shalit family much about Gilad. Hamas has refused to allow the Red Cross access to him. The family have, by circuitous means, received a total of three letters from him; and each time it seems that Shalit will be exchanged in a prisoner swap, either Hamas ups the ante or the Israeli government apparently loses its nerve as to how many prisoners it is ready to give up for this lowly and hapless soldier.
The usually mild-mannered Noam is exasperated when asked if he thinks his government is doing everything it can to secure the freedom of his son. "Of course I am not satisfied," he says. "I will only be satisfied when he comes home. There seems no hope that we can depend on" - and he has tried many avenues, from ex-US president Jimmy Carter to Ghazi Hamad, the Hamas spokesman of the Palestinian Authority.
"Basically Gilad is a strong person," he says. "He is stubborn and I think he can survive this suffering, and hold on: but in this situation you can never know. There are some army units which prepare soldiers for being captured, especially pilots, but that wasn't the case with his unit." Noam says: "We have had support from many people in Israel, who have written letters, made phone calls." Poignantly, one of the supporters has been Miki Goldwasser, the mother of one of the two soldiers captured and killed by Hizbollah, just after Gilad's abduction. Now, Noam says, he is trying to organise all the groups which want to help.
"I also want non-Jews to join us," he says. "Gilad is also a European and I want to raise this issue and the fact that he has been kept for more than two years without access from the outside world. It is against all human rights laws. I want the British government to say that it is not acceptable for him to be held like this; and I want Amnesty International to press his case. All I want is just to bring back Gilad."
Noam Shalit will appear at a rally in his son's name on Sunday, September 21, at the Lyric Theatre, London W1. Details at www.spiroark.org