Revealed: what the tearful President told the grieving relatives of Britain's war dead

It was an unscripted moment in a morning of minutely choreographed state ceremony. It was the moment the three-year-old son of a British soldier killed in Iraq looked President George Bush in the face and said: "My daddy is up in heaven."

Mr Bush's face crumpled, and he stuttered the reply: "Oh, I'm so sorry."

Beck Seymour had, in one short sentence, disarmed the world's most powerful leader and caught the emotions of a room full of war widows and grieving families.

Beck was with his mother, Lianne Seymour, the widow of Commando Ian Seymour, a young soldier killed in a US special forces helicopter crash on the opening day of the Iraq war. And, alone among the 17 other parents, widows and soldiers alongside her, she challenged the President on his policies in Iraq and failure to find Saddam Hussein's alleged stockpile of chemical and biological weapons.

"He came and spoke to me, and he just said: 'I'm so sorry for your loss', and I didn't say anything," she said. "I just looked him straight in the face. He said 'it must be terrible for you', and I just said 'you have no idea how hard it is'."

The Seymours, from Poole, Dorset, were part of a carefully selected group of 19 people - the relatives of Britain's war dead and serving soldiers - chosen to meet Mr and Mrs Bush last Thursday morning during an official visit to honour Britain's war dead at Westminster Abbey.

Mr Bush and his wife, Laura, had arrived at the abbey for a short, sombre service to lay a wreath on the Tomb of the Unknown Warrior, sign the visitors' book and receive a talk on the history of the building.

The abbey ceremony is a routine part of every state visit. But on Thursday, Mr Bush departed from protocol by arranging a private and emotion-charged meeting with the relatives of British marines, airmen, sailors and soldiers killed in Britain's most recent war - Iraq. It was an event where the President used his home-spun personal style to great effect. He won over each family - even Mrs Seymour.

The families gathered in the 14th-century wood-panelled Jerusalem Chamber of Westminster Abbey. The Bushes swept in with a small entourage, including White House officials, a senior family welfare officer from the Ministry of Defence and the President's photographer.

Mr Bush greeted each family in turn, took their hands, grasped their shoulders, and immediately passed on his condolences. Tony Maddison, the step-father of Marine Chris Maddison, killed in a "friendly-fire" incident near Basra, had travelled with his wife Julie from Scarborough with plans to ask the President how he planned to solve the dire situation in Iraq.

Mr Maddison, however, was tongue-tied and over-awed by their three-minute chat with the President. "I would say he's the most genuine guy I have ever met," he said. "He's much lampooned - people take the mickey. What a genuine guy. I have a totally different opinion ... there was a tear in his eye.

"He took the initiative away, he came across so genuine. He wasn't there for arguments or opinions. He was there to give his condolences to us. We were introduced by the welfare officer and then he spoke to us and told us that we will prevail and we wouldn't be beaten by just thugs and terrorists, and he passed on his heartfelt condolences."

Mrs Seymour had steeled herself for the meeting and took several breaths before she began talking. She told the President: "I have a three-year-old little boy who I have to bring up completely on my own now and the papers and the press are constantly reporting that there are no weapons of mass destruction. You and Mr Blair are constantly trying to reaffirm the fact that this isn't all in vain. I have to see that every day, on top of grieving for my husband." At this point, she said, "Beck chirped up and told him his 'daddy was in heaven', and Mr Bush's face just like fell, and he said, 'Oh, I'm so sorry'.

"I just said at the end of the day, my husband went away and his last words to his little boy were 'I'm going to make this a better world for other little boys and girls'. I said [to Mr Bush] 'that's your duty now, you've got to make sure that happens'. And he's like 'I promise to do my best.' That was that really, he just went to talk to the others, and then came back for photos, which was very awkward."

The meeting was, she said, "very strange" and "bizarre". But the tense and sombre atmosphere was lightened by her son. "Beck was very much the ice-breaker. He lifted the spirit in the room. He was running around and looking out for helicopters and snipers up on the roof. He gave everyone something else to focus on. I don't think the President was expecting to see any children there. It's the true reality of the situation isn't it?"

The meeting was ultimately unsatisfactory, she said, since even the US President could not bring her husband back. Yet even she was disarmed by him. "It's really hard, I don't like to say this, but I actually think he was quite genuine. He seemed genuinely quite upset and quite emotional. His wife didn't say anything to me. I don't think I heard her speak once, and to be honest, she looked the disengaged one.

"I only ever judge people when I meet them. And although I don't like his politics or what he's done, as the person I saw stood opposite me, I actually think I would get on well with him if I met him at a dinner party. I think he would be easy to get on with, he's very personable. But that's different from his politics."