What is the title of this pre-teen novel? About World War II, ships taking kids to Liverpool to keep them safe?

Im a little fuzzy on the details, but I think the main character was a boy, and it starts (Im assuming) in London, where the raids happen all the time, and his family hides in their bomb shelter. Then they send him to Liverpool with a ship that is taking hundreds of other kids there to keep them safe. On board the ship, things start to go awry when the adults have disagreements and I think there is a change in command. The kids are basically left to fend for themselves. Im not sure if the ship actually makes it to Liverpool, I think it might crash or something.
If anyone knows what book this is, I'd greatly appreciate it if you told me the title.
Thanks!