Am I missing something or is BaseCamp not suitable for planning walking routes off roads. It keeps auto routing around roads every time I place a route point on a footpath (UK 1:50K map), which is of course most of the time. I have seen a post about creating vias but that seems completly impractical. It must be possible to default to direct tracks between points on a route. If not I'm afraid I'll have to uninstall and find a different way.
Sure it is, I use it for walking routes every week. However as you have the OS 1:50K maps, and assuming these are the Garmin GB Discoverer maps, they are not routeable so you need to use the direct routing profile. Anything else will use the underlying City navigator road map, which is routeable. This is why you're seeing the auto routing around roads.
What about the OSM (Open Street Map) and the OFM (Open Bicycle Map). Maybe the OFM gives better result although it's for cycling it's routable. http://www.openfietsmap.nl/downloads/europe
I used OpenFietsMap near Zwolle, NL. It works ok for bikes but some small paths, good for walking, doable for bike are not routable. Try it for yourself.