Although OpenStreetMap in the United Kingdom, and specially in London, has come along very far, it is going to be nearly impossible to keep things up-to-date. We use a few external datasets to compare against to check for completion, and one of those is OS Locator. The fine folk at ITO World have created a comparison algorithm between OpenStreetMap and OS Locator, which they expose through a summary per area and a tile-layer as a visual aid.
I usually have to travel quite a bit from home to actually see a discrepancy, but since the update to the latest data set I actually found one very close to home: Opal Mews. On the site the discrepancy looked like:
In this case, the tag is simply missing on the way. However instead of adding the data directly from OS Locator, a survey is required. In some cases, the data in OS Locator is actually wrong, even though it's supposed to be an official source. So I went past the road, checked whether the name "Opal Mews" was visible, and added the name to OpenStreetMap: http://www.openstreetmap.org/browse/changeset/19136631
Now ITO World's OSM analysis does not have it listed as an inconsistency anymore:
One down, 18 thousand to go!