@Ruth_Mottram @organicmaps agree Organic Maps is very good for walking and I've also used it successfully for biking when I didn't have my bike computer.
Worked well both in Devon and Austria.
I have found some small errors in what is presumably the underlying Open Street Maps where roads aren't joined and it plots a very roundabout route instead. Also some trails I wanted to use were marked private on the ground so not usable. Still can't work out how to contribute and put these right.