The "PNFS Geodata Project" is me (Mike Barnes) taking the rights-of-way data available at rowmaps.com, supplemented by various other data and mapping software, and seeing what can be done with it that could be of use for PNFS volunteering activities. Using that data I created the "applications". They are not official Society products. I wrote them for my own use on a high-performance PC using the latest Firefox browser. They weren't designed with other computers or users in mind. But you're welcome to use them and I hope they work well for you. If not - sorry.
I'm using what I believe to be the latest and most accurate digital data available. However, for various reasons including manual digitisation by the highway authorities, and subsequent processing errors, some paths' identities and routes are incomplete, inaccurate, or out of date. Also the OS Explorer map is probably not as up to date as it might be. If you find something amiss, be alert to the possibility of error. The only truly reliable source of path data is the (paper) definitive map held by the Highway Authority.
There is no data for these highway authorities: Bradford, Derby, Halton, Knowsley, Leeds, Liverpool, Sheffield, Stoke-on-Trent.
The data that these applications use is constantly changing. You might be looking at out-of-date data. Take careful note of the dates on which the data was supplied. You'll see that some data is several years old.