Slim_Slang, I'll take your bet. I doubt any of the 4 others were actively using a GPS. Or if they were, that it was a nav error as compared to a planning or understanding issues (some people, believe it or not, don't seem to understand you need a clearance to fly in the TMA or
CTR
)
Roffa - The LHR point is probably about the 'large' surface area of the zone vs. US airports - A point that is done to death and not that relevant in discussing why PPLs bust clearly marked (if large) zones.