Juliet writes to Amelia that the sun is out; she's trying to avoid looking at the rubble so she can pretend London is beautiful. She mentions Dawsey's letter telling her about Christian and laments that the war goes on and on. In closing, Juliet writes that she's watching a man paint the door of his house and the man is letting two little boys help him—possibly, evidence that there is an end to the war.
For Juliet, the children represent the future and the end of the war. Especially since these little boys are helping to paint a door and make London beautiful again after the Blitz, this suggests that the children in England will be a major force in helping the country recover.