I downloaded a 40 x 40km area, I called it a tile for ease of reference. Having read a bit more, it seems you have to be logged in to retain downloads, once logged out, they are deleted. Log in, start again, if you happen to be out on the road in the pouring rain and no data signal - what then? It's too tedious. How do I remain logged in? I can't see a way.
I'm looking at alternatives. Maps.me is beautifully simple and uses OSM, download once, no account or log in nonsense needed. I've tried it today, it works. I plotted a route in ridewithgps, exported it as a kml file and dropped that file into the maps.me folder - shows as an overlay on the map, just as I did with VR. I'd prefer Open Cycle Map, but I can't find an app that uses these offline as yet.
I'm also trialling the OS app, also works offline no problem. The 2 week trial version doesn't seem to give 1:25k, and zooming into 1:50k is hit and miss on detail (I understand OS is raster, not vector, so doesn't scale terribly well). They also do a free version, with a simpler vector map, but the colouring is poor in my view, but it works and as a free standby it's useful to keep.