I have been trying to find a book I read in the mid 1990s. It was about the build up to a nuclear war and finished with the characters looking up at the sky and seeing the streak of the bombs (or possibly just knowing the bombs were coming - I might have imagined the rest). I think there were two teenage characters in a star-crossed lovers type relationship - possibly one was of Chinese origin. It was set in a real city in England. The final scene was at a 'Stop the Countdown' rally which ended when someone announced that the war had started, people started running away, and I'm pretty sure that it ended with the two characters holding each other as they looked at the sky. The downbeat ending really seared itself on my mind.
I have been through the wikipedia list of nuclear war related fiction, but with no luck. It is possible it was a short story, but it was definitely in a book in the upper school library, so probably aimed at 14-18 year olds. It would be wonderful if someone recognised it!