Hi Berlin
Quite a lot of aircraft have their GPS reporting offset.
I regularly watch G-CELJ landing at EGNH about 500m short of the runway, and about 200m to the left. Doesn't seem to do it any harm, though. I also see aircraft at EGCC taxying through the woods to the south of runway 2.
I presume that it's just a setup error - when aircraft start using ADS-B for collision avoidance, it's going to be quite a problem!
Rod
PS the font I use for the map is Verdana Ref - Verdana fonts are designed for screen legibility - things like Times and Arial are designed for printing, and MS Sans and Courier are designed for programmers (and keeping columns lined up).