Let's clear up a few things
@Bruno Girin: There ain't a lot of point in building cycle routes if no-one knows where they go! Sustrans have been supportive of OSM and vice versa: in fact, a good number of OSM contributors are volunteer Sustrans rangers.
@Anonymous Coward ("OS Copyright"): Your understanding is wrong. It's an infringement to copy OS data (potentially of 'database right', not copyright), but not an infringement to independently research the same facts - which is exactly what OpenStreetMap is doing.
@Anonymous Coward ("You can't compare OS and Google Maps"), Rick and Paul M: Don't know about Snowdon, but OSM certainly has mapped most of the main paths on (say) the Brecon Beacons. Google hasn't, but OSM's scope is much wider than Google's. Similarly, OSM mapping of the National Cycle Network is clearer and more accurate than even the OS's, though not as good yet as the AA's.
@FlatSpot, Tim Spence and Chris Duncan: As you well know, the OS gets plenty of Government money. The point is that it isn't paid in subsidy, but as payment for geodata from Government agencies (e.g. local councils) who need the data to do their statutory duty. Electoral boundaries, for example, are a fundamental part of our democracy yet are all "derived works" from OS mapping - so you can't, definitively, find what ward you're in without someone, somewhere paying the OS. Meanwhile, information on new housing developments and roads is supplied by the councils to the OS... for free.
Because the OS has an effective monopoly on such data, it is what the economists would call a hidden subsidy. Now I believe the OS produces the best maps in the world and would actually _support_ Government subsidy for them, but let's not pretend that their current dominance is the result of natural market competition alone.