There's a book I read in around 1997, aimed at 9-12 sort of range. I've been trying to find it every where but just cannot and it's driving me mad.
What I can remember (Details may be slightly wrong):
Set in WW2 a boy's home is destroyed in the blitz. He is left alone and grabs the attaché case his father kept with cash/ documents and so on. He sets off some where but I can't remember what he is aiming for. An aunt?
He somehow finds a dog, and uses some of the cash to buy a collar and lead.
He sleeps under a boat on the beach his first night alone, and uses sand to brush his teeth.
At some point he and his money gets wet, fell in the sea? And an old man finds him, takes him in and shows him how to dry his money. The old man had a dead son and there is a line that is something like "the old man had a boy shaped hole in his heart". I was very touched by this aged 10!
He gets trapped in one of those refuges on the causeway to Lindisfarne overnight.
I think at the end it turns out his family survived and are very annoyed with him by the time they find him.
Very grateful if anybody else remembers this??