I used this a few times as a booster task for more able writers, but it can be adapted easily enough for all abilities.
Be sure to have good descriptions of blitzed London and take the description of arriving at the lighthouse from the actiual story to contrast. Any GD writers should also really focus on developing the character of the narrator - i asked them to work on a theme eg home-sick, brave, protective of sibling and follow this throughout the story.
One Greater Depth writer wrote a fantastic story called The Quest For Cows on this WW2 theme – the narrator (obsessive by nature) had never seen a real cow and was desperate to see one, to the point of obsession. The train leaves London at dusk and travels through the night and it is only as it arrives at the lighthouse that he sees his first cow.