I've just received an update from Humphrey explaining the source of the data and why it varies in resolution. Because OpenStreetView is the result of community contribution it depends on the submissions made in a particular area.

I use Talkytoaster on my Garmin GPSRs. I have the whole of Western Europe with POIs on a 4gb micro SD, this also includes contours, footpaths and bridleways. Certainly enough detail for my Geocaching but I still navigate using paper maps and compass.

Thanks for all the input. Humphrey has given me something to think about and I am researching that. Thanks Peter for the heads up on talky toaster. Completly concur on the paper maps. I do love them maps that is.