I did a lot of reading last month. Partly enabled by reading young adult fiction which does go really quickly. I got a bee in my bonnet (huh, again?) about a book that I read when I was young which included a boat ride along a canal and through a lock. That was all I could remember, and that they were on the run. I consulted the good people on AbeBooks BookSleuth forum - cannot recommend this enough if you are searching for a lost title with only the slightest notion of the content; the collective knowledge or readers is amazing - and found what I was looking for!
The Silver Sword by Ian Seraillier - A book I certainly read when I was younger and I thought was the canal book but no. There is a canoe ride down the Danube and, curiously, for a book about post-WWII displacement and prison camps, no mention of Jewish people whatsoever.
Ashes to Dust by Yrsa Sigurdardottir - Icelandic crime thriller, a good one but I did guess one of the plot devices way in advance.
A Stranger in Mayfair by Charles Finch - British historical crime thriller, a good one but again, I guessed the plot device in advance. Perhaps I'm reading too many of these?
Thursday's Child by Noel Streatfeild - My second attempt at finding the canal book. Nope, and not worth reading. Really crappy Victorian orphanage, completely two-dimensional characters. And boring.
The Girl who Kicked the Hornets' Nest by Stieg Larsson - Very long and read in three days. Great.
The Devil's Children and Heartsease by Peter Dickinson -These are parts one and two of the Changes Trilogy. Fantastic slightly science-fiction/fantasy, dystopic future setting, great characters, great writing. And yes, Heartsease was the canal book of my youth.