2.8 introduces the Primary Road Network highlighter option, using the PRN data distilled from the VectorMap District dataset.
Similarly to how the Locator data is handled, the PRN data is stored in 20km x 20km blocks which are loaded from my server and then cached locally as you pan around the map. Blocks are removed from the cache if not accessed in the last 10 minutes. Note that when a new PRN block is requested from the server, the script doesn't automatically redraw the PRN layer after the block has successfully loaded, so if the highlighting appears to have stopped short of where you'd expect it to stop, please try moving the map view slightly to force a refresh of the highlight layer. Having said that, sometimes the PRN really does stop short of where you might think it would
Note also that there are the occasional very short isolated segments which have been defined as PRN in the VectorMap District data, but which are not shown as part of the PRN in other OS data. So far all the ones I've seen have been completely obvious, so there doesn't appear to be any risk in leaving them in the data (and besides, I can't really be arsed to manually proof-read all of the data
Firefox+Greasemonkey version: https://greasyfork.org/scripts/1941-wme-to-os-link
Chrome packaged version: https://chrome.google.com/webstore/deta ... mdbdnmcfei