Thingummy

Don't see why not.  Councils have legal responsibility to publish a definitive map. This is Cambridgeshire's in Digital form, paid for by our taxes, I am sure it is public domain.  (I have seen other councils base theirs on Open OS, which would be the same. Obviously if it said an owner other that the council or looked like a "google map" or "Here map" etc I would search elsewhere. Incidentally, I am seeing OSM maps used by councils too, in very little changed form, so they can't be too fussy.