I saw this (see below) in review and was suspicious due to not appearing on streetview, so I check the sustrans map. NCN 6 does go through Leighton Buzzard, but nowhere near this street, which is at the top left below East Street
Both markers are in very good condition. The supporting photo was not the same as the main photo, suggesting actual stickers put on to get home pokestops rather than AI.
@NianticAaron Can submissions from this person please be checked since they are fakes. One of them has already made it into the game (51.919643, -0.656160 “National cycle network route 6”).
NCN 6 does not go along these roads and the route markers are photoshopped.